Original air date: April 29, 2006
Production code: 2.3
The one where the new series meets the old series when an old friend makes a comeback.
Written by Toby Whithouse.
The return of Sarah Jane Smith and K9 Mark III, who last appeared on-screen in "The Five Doctors" in 1983. This episode pretty much singlehandedly spawned The Sarah Jane Adventures, giving another generation of children the gift of Elisabeth Sladen. It also holds significance as the first episode of the modern era of Doctor Who to absolutely, explicitly confirm that the new series was set in the same continuity as the 1963-89 original series (prior to its broadcast, fandom was split on this issue, though the producers never were).
At Deffry Vale High School, the headmaster, Mr. Finch, notices a student waiting outside his office. She has a headache, and cannot simply go home because she lives in a children's home. Finch offers his sympathies, realizing that there is no one to miss her, and invites her into his office; it is nearly time for lunch, after all. The door closes, then there is a flap of wings, and the girl screams.
We see that the Doctor and Rose are undercover at the school. The Doctor is doing so by taking up a job as the new physics teacher. He asks a few simple questions. Only an intelligent student called Milo can answer. After a few basic questions, the Doctor advances to higher levels of knowledge, finally asking how to travel faster than light. Milo answers every question without missing a beat.
Over lunch, he convenes with Rose, who is working as one of the serving ladies (and very much displeased at her undercover job). The conversation establishes that they're here because Mickey tipped them off about suspicious activities going on here, and the Doctor is convinced that the tip is good. Everyone at the school is well-behaved and there is something odd about the chips. Rose eats a few, saying she enjoys them. The conversation is interrupted as the head dinner lady comes over to chide Rose for leaving her post. The Doctor gets her to reveal that the school menu has been designed by Mr. Finch himself to improve concentration and performance. As Rose leaves, the Doctor sees another teacher, Mr. Wagner, approach another student, Melissa. He tells her Milo has failed him, so she is being moved to the top class. He also summons another student, Luke, but not Kenny, who is not allowed to eat the chips and has a packed lunch from home. The Doctor looks up and sees Mr Finch gazing down on the cafeteria floor, watching everything like a hawk.
In the kitchen, Rose watches the other kitchen staff, all wearing gloves and face masks, bringing in a large barrel of oil. One of the ladies warns them not to spill a drop. She gets a call from Mickey, who wants to check in to mention that he's uncovered reports of massive UFO activity in the area around the school three months ago. However, his investigations are being blocked by something called Torchwood. Rose, in turn, realizes that lines up with something she's heard: the kitchen staff were all replaced three months ago with new personnel, at the same time Finch showed up. The conversation is put on hold when the barrel slips, spilling the oil on one of the staff, who starts to burn. The rest usher her into a side room and shut the blinds. Rose starts to phone for an ambulance, but is told by the head lady not to worry, she is all right, even as Rose hears screams and lots of smoke billows out of the side room. Apparently she just does that sometimes. Rose glances down at the barrel, which is leaking a golden, oily substance.
In the maths classroom, Mr. Wagner tells the children at their computers to put on their headphones. The screens flicker on. The monitors display a green, rotating cube with rapidly scrolling, alien-looking symbols and seemingly random text on the right. The children type on their keyboards with incredible speed. Clearly, something is very wrong.
Mr. Finch receives a visit from a journalist, Sarah Jane Smith, who is interested in writing a profile on him. Finch explains that one of the policy changes he has made is free — but compulsory — school dinners.
While this is going on, the Doctor is in the staff room speaking to Mr. Parsons, head of the History department, who tells him of the extraordinary knowledge of his students since Finch became headmaster. One of his students gave him the exact height of the walls of Troy in cubits. But there's also been some very strange staffing shifts. The day after Finch arrived, just three months ago, seven teachers came down with flu, and were replaced by new hires of Finch's. Except for the one the Doctor replaced, who somehow won the lottery despite the fact that she never played (the Doctor is implied to have been behind that one). Mr. Finch brings Sarah into the staff room. When the Doctor sees her, he smiles delightedly and has an enormous internal squeal at unexpectedly seeing his old friend, but introduces himself as John Smith. Sarah remarks that she once knew a man who went by that name. When she learns "Smith" is a new teacher, she asks if he has noticed anything odd. She has lost none of her inquisitive nature, and the Doctor is elated, although he does not reveal his real identity to her.
As the Doctor wanders the halls in a slight nostalgic haze, Kenny goes into the maths classroom. He is shocked to glimpse a bat-like creature under one of the desks. Noticing him, the creature transforms rapidly into Mr Wagner. Wagner tells Kenny to leave and the boy hastily flees the room.
That night, Sarah Jane Smith, having quite correctly worked out that something strange is definitely going on, breaks into the school to explore, and the Doctor, Rose and Mickey do the same. The Doctor sends Mickey to the maths room and Rose to get a sample of the oil, while he checks the headmaster's office. There are sounds of flapping and the occasional shriek. Winged shadows flit across walls.
Sarah, trying to break into Mr. Finch's office, notices she is being watched. Running, she eventually enters a gymnasium storeroom — where she finds the TARDIS. As thirty years come roaring back to her, she backs out of the room into the gym and guess who she finds? They exchange pleasantries which are cut short by a piercing scream. They meet Rose along the way. The Doctor introduces the two, and Sarah comments on Rose's youth.
The scream turns out to be Mickey, who has opened a cupboard full of shrink-wrapped rats. Sarah suggests the rats are for dissection, suggesting cattily that maybe Rose isn't old enough to have gotten to that point in school, but Rose retorts that rat dissection hasn't been performed in schools for years, making a snide dig at Sarah's age. As they head back to Finch's office, and Sarah and Rose begin to bicker, Mickey laughs and tells the Doctor, "The Missus and the Ex — welcome to every man's worst nightmare!"
The Doctor suggests that the rats may be food. When they enter Finch's office, they find what that "something" is: 13 large, bat-like creatures hanging from the ceiling, asleep. They back out hurriedly, but as the door shuts, the one next to Mr. Wagner wakes and shrieks. Outside, the Doctor tells the others that when Finch arrived at the school he brought twelve staff members with him, so they've got thirteen giant bats to deal with. He is then about to head back in despite the danger so he can use the TARDIS to analyze the oil sample Rose procured. Sarah tells the Doctor she may have something better: to the Doctor's excitement, in the trunk of her car is an inactive and rusty K9 Mark III, with one of his side panels missing.
Not knowing that they are being trailed by Mr. Finch and another bat-creature, they go in Sarah's car to a nearby café, where the Doctor repairs K9. Mickey teases Rose about her jealousy, while Sarah asks the Doctor if she did something wrong since he never came back for her after his visit home. In an intense moment, the Doctor tries to brush it off, saying that she was getting on with her life, which Sarah disagrees with, as the hardest thing for her was adjusting back to mundane life after all she had seen.
K9 comes to life and recognizes the Doctor, who smears some of the oil sample on its eye sensor. K9 identifies it as Krillitane oil. The creatures are Krillitanes, a composite species who take the best physical parts of other species they conquer. The Doctor did not recognize them at first because the last time he ever met them, they were essentially humans with giraffe necks.
As they leave the café, Rose is struggling to come to terms with the realization that she's not the first person the Doctor travelled with. She tells the Doctor about her anxiety and fear that he'll abandon her. The Doctor promises he will not just leave her, explaining that he did not go back for Sarah because it would have been too hard: "I don't age. I regenerate. But humans decay, you wither and you die. You can spend the rest of your life with me. But I can't spend the rest of mine with you. I have to live on, alone. That's the curse of the Time Lords." Mr. Finch hears the phrase "Time Lords" and sends the other Krillitane to swoop over and scare them.
The next day they all return to the school. The Doctor sends Rose and Sarah to discover what is inside the computers, and Mickey to stay in the car with K9 as surveillance — a task Mickey compares to being "sent to the back of the class with the safety scissors and glitter". The Doctor himself is going to have a word with Mr. Finch.
The Doctor and Mr. Finch confront each other at the swimming pool. Finch confirms he is a Krillitane, real name Brother Lassar, and the wings are a recent addition to their form. What the Doctor sees as human is just a morphic illusion. Surprised to see a Time Lord, Finch derogatorily calls them a race of pompous, dusty senators, afraid of change and chaos and now all but extinct. He can sense that the Doctor is different but still refuses to reveal his plans, challenging him to work it out.
Working on the computers, Sarah and Rose playfully argue about who has had more experience time travelling, swapping the names of the different monsters they have met. Sarah settles it when she mentions she met the Loch Ness Monster, but they soon realise the argument is pointless and bond by comparing notes on the Doctor (Sarah is very amused to hear from Rose that the Doctor still strokes parts of the TARDIS), bursting into laughter when he enters and confusing him.
Finch tells the other Krillitanes that they are moving to the final phase. The school will be sealed and they will become gods. Even though it's break time, the intercom calls all pupils to class and the staff to the staff room. All the pupils appear strangely happy that the break has ended early, except Kenny, who hesitates, but eventually follows the others inside. The Krillitanes begin their plans by devouring the rest of the staff.
In the maths room, the Doctor finds the computers fixed with a deadlock seal which the sonic screwdriver cannot breach. Finch seals all of the school's exits while Mr. Wagner activates the computer program, which the children begin working on again. Kenny cannot get out of the school, but he attracts Mickey's attention. Mickey reactivates K9, asking him if he has some way to get through the locked doors in the school. K9 reminds him they are in a car. It takes Mickey a few minutes to process that K9 is suggesting he break down the glass by using the car as a battering ram.
Rose, Sarah and the Doctor watch the symbols flash on a large screen. The Doctor works out that the Krillitanes are trying to solve the Skasis Paradigm, the Universal Theory. Whoever cracks it can control the building blocks of the universe, all of time and space. The Krillitanes are boosting the children's intelligence with the oil, using them and their imaginations as a giant processing device. Finch appears at this point, asking the Doctor to join them, tempting the Doctor with the ability to change the universe, to save everyone, even restore the Time Lords. He offers Sarah and Rose the chance to travel with the Doctor forever, never growing old. The Doctor appears tempted, but Sarah tells him that pain and loss define them as much as happiness or love. Everything has its time and everything ends, whether a world or a relationship. The Doctor picks up a chair and hurls it at the screen, smashing it. He tells Rose and Sarah to get out.
Mickey and Kenny rush to the pupils. Finch shrieks, summoning the other Krillitanes, who transform into their bat-forms. Mickey and Kenny meet up with the others and run into the cafeteria, chased by the Krillitanes. Finch tells his brothers he wants the Doctor alive, but to eat the others. As the Krillitanes attack, K9 shoots down one of them with its blaster. The Doctor tells K9 to hold them off while they retreat. However, K9's battery is failing and Lassar tells the Krillitanes to ignore the shooty-dog thing and get the others.
In the physics lab, the Doctor realizes that the solution to the problem is the oil. The Krillitanes have changed their physiology so often that even their own intelligence-boosting oil is toxic to them now. The Krillitanes start bashing down the door. The Doctor tells Mickey to get the children unplugged and evacuated. Kenny triggers the fire alarm, the high-pitched sound hurting the bat-like ears of the Krillitanes and stunning them long enough for the others to get past to the kitchens. However, this doesn't work for long. Lassar simply punches through the wall and rips out the power lead to the alarm.
So Mickey has to unplug the computers and gets the children out of the school. In the kitchens, the Doctor finds the barrels of oil are deadlock sealed. While the others flee, the Doctor and K9 stay behind. K9 tells the Doctor that the barrels will not withstand a direct hit from his laser, but as his batteries are weak, he has to remain. The Doctor protests, knowing that K9 will be caught in the explosion, but the dog replies there is no alternative. Sadly, the Doctor bids his old friend goodbye, calls him a good dog and exits the building. The Doctor takes Sarah's hand and drags her away from the school while she asks about K9.
Brother Lassar and his brethren enter the kitchen in human form, searching for the Doctor. Lassar mocks K9 when he sees him, but K9 shoots a barrel, spilling the toxic oil over the aliens. Lassar snarls to K9, "You bad dog"; the dog replies, "Affirmative". The explosion takes out a large chunk of the school and K9 with it. The pupils cheer the school's destruction and hail Kenny as the hero who did it. Sarah weeps over K9's sacrifice as the Doctor comforts her.
Later, Sarah enters the TARDIS in a park. The Doctor suggests that Sarah join them, but Sarah declines, saying it is time she found a life of her own. Mickey, though, insists on going along, feeling that he's had enough weird experiences to become an actual companion, rather than a "tin dog". With a little prodding from Sarah Jane, the Doctor agrees although Rose is less enthusiastic about the prospect. Before leaving, Sarah Jane tells Rose she'll be there for her when she needs her. As for the Doctor, Sarah asks only for one thing, something thirty years overdue:
The Doctor: Goodbye — my Sarah Jane.
He vanishes again, but leaves Sarah Jane with two things: long-awaited closure, and a new K9 model. However, this isn't the last we've seen of Sarah Jane.
- Actor Allusion:
- Anger Born of Worry: Sarah Jane's reaction upon realizing who the Doctor is after her initial joy is "I thought you died! I waited for you, and you didn't come back, and I thought you must have died!"
- Arc Words: Torchwood blocks Mickey's search for pictures of the UFOs at Deffrey Vale.
- The Assimilator: The Krillitane alter their DNA with DNA from races they conquer.
- Badass Adorable: K9, the toy-like robot dog with the lasers. Him being voiced by John Leeson doesn't hurt.
- Bat People: The Krillitane, this episode's Monster of the Week, are a species able to integrate physiological features from other races they conquered, with their most recent addition being bat-like wings along with other chiropteran behavior such as sleeping by hanging upside-down and eating rats.
- Better Partner Assertion: A non-romantic example. When the Doctor's current companion Rose Tyler meets former companion Sarah Jane Smith, they both become deeply insecure — Rose is upset to learn that the Doctor has had many companions and left them behind, while Sarah Jane feels her age because Rose is so much younger than her (it doesn't help that the Doctor's tenth regeneration is also extremely young). The women eventually get into a verbal sparring match by bringing up the various monsters and adventures they've met on their travels, each trying to prove that they're the superior companion and friend to the Time Lord. Sarah Jane wins by citing "The Loch Ness Monster," which Rose finds amazing.
- Beware the Nice Ones:
- The Tenth Doctor effectively sums up the direction he will be taking this regeneration in a single sentence.The Doctor: I'm so old now. I used to have so much mercy. You get one warning. That was it.
- The Tenth Doctor effectively sums up the direction he will be taking this regeneration in a single sentence.
- Big Bad: Mr Finch.
- Big Damn Heroes: K9, of all things, saves everyone by application of laser blasts.
- Big Damn Reunion: More of a subdued reunion: the Doctor reunites with Sarah Jane Smith, although she doesn't know he is the Doctor... till later in the story when she sees the TARDIS.The Doctor: [wistfully and gently] Hello, Sarah Jane.
- Blatant Lies: One of the cafeteria workers gets oil all over herself and is quickly rushed off into another room. Rose is calmly informed by the head dinner lady that she's quite all right. Immediately, the worker screams and smoke billows out of the room.Dinner Lady: It's fine. She does that.
- Brick Joke: A brick thrown thirty years ago finally lands; when we last saw Sarah Jane, she suspected the Doctor had left her in the wrong part of Britain. Turns out that, in fact, he had... by 914 kilometres.
- Buffy Speak: "Forget the shooty dog thing." Said by Giles.
- The Bus Came Back: Sarah Jane Smith and K9 return after a 23-year absence.
- Butt-Monkey: Lampshaded, as Mickey compares Rose to Sarah Jane, and himself to K9 in their relationship with the Doctor...Mickey: So what's the deal with the tin dog?
Sarah Jane: The Doctor likes travelling with an entourage. Sometimes they're humans, sometimes they're aliens, and sometimes they're tin dogs. What about you — where do you fit in the picture?
Mickey: Me? I'm their Man in Havana, I'm their technical support, I'm [realization dawns] Oh my God: I'm the tin dog.
- Call-Back: K9's repeated stating of "we are in a car" in response to Mickey trying to figure out if there's a piece of technology they can use to break into the school appears to hark back to a similar moment in the 1996 telemovie, in which the Master simply solved Chang Lee's dilemma of how to surmount a police barricade by shouting that they're currently in an ambulance.
- What does Sarah Jane say to K9 as they walk off at the end of the episode? "We've got work to do." Word for word what the Seventh Doctor said to Ace as they walked off at the end of the classic series.
- Cannot Spit It Out:The Doctor: Imagine watching that happen to someone that you–
Rose: What, Doctor?
- Captain Obvious:Mickey: Okay, no time to explain, we need to get inside the school. Do you have, like, I don't know, a lock picking device?
K9: We are in a car.
Mickey: Maybe a drill attachment?
K9: We are in a car.
Mickey: Fat lot of good you are!
K9: We are in a car.
Mickey Smith: Wait a second. We're in a car.
- Car Fu: When Mickey gets locked out of the school and needs to get back in, he manages to reactivate K-9 and asks if he has some kind of lockpicking device, only for K-9 to remind him they're in Sarah Jane's car. Repeatedly. "Fat lot of good you are... wait a second. We're in a car."
- Cargo Ship: Mentioned by Sarah Jane. Sarah Jane: Tell me, does he still... stroke bits of the TARDIS?
Rose: Yeah, yeah, he does! I'm like, "Do you two want to be alone?
- Cat Fight: Not the physical Fanservice-type, but Rose and Sarah Jane engage in a verbal pissing contest through much of the episode. In the end, the women come to a (very giggly) compromise when they start comparing the things about the Doctor that bug them, which in turn makes the poor Doctor wonder if them getting along isn't even worse for him, since now they seem to be in conspiracy against him. As Mickey so aptly puts it:Mickey: Oh mate, The Missus and the Ex! Welcome to every man's worst nightmare.
- Climactic Music: The relentless, intense chanting that is first heard when Mr. Wagner first plugs the children in for their computer work, and then during the episode's climax, as the Krillitanes chase the Doctor & Co. through the school.
- Comically Missing the Point: "Aberdeen... that's next to Croydon, isn't it?"note
- Continuity Cavalcade: Sarah Jane and Rose trying to one-up one another regarding who's had the most outlandish adventures with the Doctor. Sarah Jane wins.Sarah Jane: I saw things you wouldn’t believe!
Rose: Try me.
Sarah Jane: Mummies.
Rose: I’ve met ghosts.
Sarah Jane: Robots. Lots of robots.
Rose: Slitheen. In Downing Street.
Sarah Jane: Daleks!
Rose: [smugly] Met the Emperor.
Sarah Jane: Anti-matter monsters!
Rose: Gas mask zombies!
Sarah Jane: Real living dinosaurs!
Rose: Real living werewolf!
Sarah Jane: THE. LOCH NESS. MONSTER!
Rose: [finally outclassed] Seriously?
- Continuity Nod:
- Sarah referring to the Doctor's companion as his "assistant". When Sarah met the Doctor he was stuck as UNIT's scientific advisor, hence he had lab assistants instead of (travelling) companions. It's also a retro touch on a metafictional level, as even though it was used in the show as far back as the '60s, "companion" didn't become the borderline-official term for non-Doctor main characters until the 21st century, and up to the 1980s "assistant" was more common, especially among the production crew.
- The Doctor tells Sarah that he couldn't take her to Gallifrey "because back then, humans weren't allowed". This handwaves the fact that later Classic Series serials had the Doctor bringing his companions to his homeworld without issue.
- Creative Sterility: The Krillitanes are using human children to crack the paradigm because it requires imagination, something the children have much more of than the Krillitane.
- Cut the Juice: After getting inside the school, Mickey finds all the kids typing away. After being unable to get their attention, he finds the plug, looks around as though expecting a more dramatic solution, and then just pulls it out. He gets a few sparks thrown at him, but that's it.
- Deadly Euphemism:
- Mr. Wagner informs Melissa that she's moving up to the top class because Milo's failed him. Milo, as in the student the Doctor was questioning in class at the beginning of the episode, and who isn't seen again...
- Mr. Finch and his brothers "taking an early lunch" by eating the rest of the staff.
- Deadpan Snarker: K9 regularly snarks.Mr. Finch: You bad dog.
- Death of a Child: Within the first two minutes of the episode, Finch kills and eats an orphaned girl no older than thirteen.
- Disney Death: K9, although it is unclear if this is the same robot rebuilt (with the same personality and memories) or just another robot of the same model.
- Does This Remind You of Anything?: The Doctor taking on a string of pretty young companions, only to discard them without regard to their feelings because they're getting too old, makes the Doctor look like a Dirty Old Man having a midlife crisis or an irresponsible Casanova. Not that David Tennant would ever play Casanova...
- Early-Installment Weirdness: Sarah's travels with the Third and Fourth Doctors are described in the broadest possible strokes, with Sarah only very briefly and vaguely mentioning encounters with robots, the Daleks, an anti-matter monster, dinosaurs, and the Loch Ness Monster in a conversation with Rose. This was back when the BBC were adamant on keeping references to pre-2005 stories to an absolute minimum — partly to avoid Continuity Lockout, and partly to avoid paying royalties to the writers of older stories — with later relaunch stories being more willing to directly discuss the events of stories from the classic series.
- Evil Principal: Headmaster Finch is leading the Alien Conspiracy of the week, turning his students into Wetware CPUs, and occasionally eating a student he thinks nobody will miss.
- Evil Plan: One more villain with a god complex. After incorporating so many species, the Krillitane want to become gods.
- Failed a Spot Check: Mickey asks K9 for lockpicks to get past locked glass doors.
- Faux Affably Evil: Mr. Finch is always so polite, and charming. Even as he's planning to eat orphans, or have his brethren eat the Doctor's friends. However, he does seem genuine in his desire to have the Doctor join him, if only slightly annoyed when the Doctor turns him down.
- Flanderization: Due to how Russell T. Davies tended to write most of the female companions during his run, Sarah Jane comes off more as a jealous ex than an old friend of the Doctor's, seemingly just to make Rose jealous, for no reason.note Granted, there was a more than twenty-year gap from the last time she met the Doctor. Mercifully, after the immediate territorial pissing match, the two women get giggly over the Doctor's idiosyncrasies and Sarah Jane is nothing more than platonic with the Doctor forever after.
- Freeze-Frame Bonus:
- The school is papered with posters encouraging the students to "EAT MORE CHIPS".
- In a rather charming split-second moment, pausing right at the end of the Doctor and Sarah's reunion shows both of them have the same "8D" grin.
- Fully Absorbed Finale: The episode picks up on the partnership between Sarah Jane and K-9 first introduced in the failed Pilot K-9 and Company and briefly seen again in "The Five Doctors". Quite simply, K-9 eventually broke down. (But the Doctor fixed him.)
- Functional Genre Savvy: Sarah Jane, thanks to having had copious amounts of experience with the Doctor's shenanigans, realizes (off-screen) that something is going on and needs to get into the school... which she achieves by doing exactly what the Doctor does: flattering the bad guy's ego.
- The Good Old British Comp: Deffrey Vale. In a variant, it's not the students who are the problem. As the Doctor notes, none of the students are misbehaving. Literally, none.
- Heroic Sacrifice: Poor K9 is lost to the explosion. Since he's a machine, however, the Doctor repairs him.
- Hollywood Mid-Life Crisis: Sarah Jane gets in some snark at the Doctor.Sarah Jane: You can tell you're getting older. Your assistants are getting younger.
- I'm a Humanitarian: The Krillitanes occasionally eat students who they don't think will be missed, as shown when Finch does so at the beginning of the episode. They're later implied to devour all of the human faculty members to get them out of the way.
- Instantly Proven Wrong: When Rose wants to call an ambulance because one of the kitchen staff gets in contact with the mysterious oil, the dinner lady in charge assures her that this is not necessary because the victim is quite alright. Cue an explosion and a scream coming from the other room.Dinner lady: She does that.
- I Will Wait for You: Sarah tells the Doctor rather reproachfully that she waited for him. He'd actually had no intention of coming back, leading to a case of self-inflicted What the Hell, Hero? for the Doctor.
- The Knights Who Say "Squee!": Sarah and the Doctor's reaction to seeing the other once again. David Tennant admitted the reason he's grinning like a madman throughout the episode is because he got to act alongside Elisabeth Sladen, who he grew up watching on the show.
- Lampshade Hanging: While on the phone early in the episode, Mickey points out that it's useless to try and hang out with Rose because they always get interrupted by something. Cue a large barrel of Krillitane oil getting tipped over and Rose having to hang up the phone.
- Long Neck: The Doctor mentions that the Krillitanes used to have extremely long necks, but due to the fact they constantly take on other species' traits, they now look like giant bats.
- Manipulative Bastard: Mr. Finch nearly talks the Doctor into joining him with just a few lines of temptation, and when Sarah Jane steps in, shifts gears at the speed of light and — based off only brief observation and some well informed guesses — almost succeeds in doing the same to her. She, however, snaps out of it and snaps the Doctor out of it too.
- Meaningful Echo: In "The End of the World", the Ninth Doctor said of Cassandra, "Everything has its time, and everything dies." The line is repeated almost word-for-word by Sarah Jane to the Doctor in this episode.
- Meaningful Name: Mr. Finch, an alien capable of developing the traits of other conquered species is named after Darwin's finches. The widely known evidence of evolution due to the differing sizes of their beaks.
- The Missus and the Ex: Trope Namer, courtesy of Mickey. Sarah Jane is the Doctor's former companion; Rose is the current one. Both of them are in love with the Doctor, and it's been implied Sarah and the Fourth Doctor were in a degree of romance.
- Mundane Solution: To get past a locked door, with coaxing from K9, Mickey just rams it with a car; then to shut down the alien-influenced supercomputer, he pulls the power plug.
- Never Say That Again: The Doctor does it to himself:"Correctamundo! ...A word I have never used before, and hopefully never will again."
- Ironically, the word was later used repeatedly by the Doctor in one of the official flash games.
- Oh, Crap!: Discovering the TARDIS hidden in the storage room off the gym really knocks poor Sarah Jane for a loop.
- "Open!" Says Me:Mickey: Okay, no time to explain, we need to get inside the school. Do you have, like, I don't know, a lock picking device?Mickey: Maybe a drill attachment?Mickey: What a fat load of good you are!
- Percussive Maintenance: Mickey rapping K9 on the head is what finally gets him going again.
- Poorly Disguised Pilot: Averted Trope. It's important to remember in the wake of The Sarah Jane Adventures that this wasn't a PDP for that show. In fact, Sarah Jane's appearance wasn't supposed to lead to a spinoff, but was more to link New Who with the old show (to prove that it was indeed a continuation of the 1963-1989 series rather than a reboot). The fact that the episode was successful and RTD decided to create a Sarah Jane spinoff was just a very happy accident.
- Powered by a Forsaken Child: The Krillitane teachers use children to crack the code because adults lack the imagination.
- Pre-Mortem One-Liner: Combined with "Facing the Bullets" One-Liner, we get this brief exchange between Mr. Finch and K9 after the robot drenches the Krillitanes with their oil.Mr. Finch: (Just as the Krillitanes are about to blow up) You bad dog!
- Punctuated! For! Emphasis!: "THE. LOCH NESS. MONSTER!"
- Reality Warper: What Mr. Finch seeks to become through the Skasis Paradigm because it will give him that power. He offers that power to the Doctor.
- Remember When You Blew Up a Sun?: Sarah Jane Smith and Rose try to outdo each other with their past adventures. Sarah Jane wins when she points out she's met...Sarah Jane: THE. LOCH NESS. MONSTER!
Rose: [beat] Seriously?
- Reveal Shot: When Sarah, stunned, backs out of the storage cupboard where the TARDIS is stashed and back into the gymnasium, there is a brilliant panning shot done to reveal the Doctor just standing there, waiting for her.
- Scary Black Man: Mr. Wagner, one of the Krillitane teachers. Even his true Krillitane form is darker than the others.
- Screams Like a Little Girl: Discussed.The Doctor: And you decided to scream.
Mickey: It took me by surprise!
The Doctor: Like a little girl?
Mickey: It was dark, I was covered in rats!
The Doctor: Nine, maybe ten years old. I'm seeing pigtails, frilly skirt...
- Screw Learning, I Have Phlebotinum!: The Krillitane oil doesn't just make the kids smarter, it also dumps a load of knowledge into their heads, such as how to travel faster than light. It's also possible that those computers they are mesmerized by are teaching them.
- Silver Fox: Sarah Jane, who may have changed over the decades, but most emphatically not for the worse.
- Snark-to-Snark Combat: Sarah Jane and Rose, and a gentler version between Sarah Jane and the Doctor, and that's not even counting the shots Mickey, Finch, K9, and the Doctor all get in at each other.
- Special Effects Evolution: While the K9 prop is exactly the same as the one used in the classic series (much to the irritation of the technicians, given the prop's infamous lack of cooperation on-set), the effects for K9's laser blasts are decidedly more convincing here than they were during his heyday, thanks to the passing of several decades and an expanded budget for the show that thoroughly outpaces what it was granted between 1977 and 1980.
- Squee: All over the Doctor's face when he first sees Sarah Jane again.
- Stock Ness Monster: During the argument between Sarah Jane and Rose over who endured the most "space stuff", Sarah Jane mentions she went up against THE. LOCH NESS. MONSTER!!!! Rose can't top it.
- Stuff Blowing Up: A Krillitane doused with their own oil will explode. K9 utilises this to blow up all of them, himself, and a good chunk of the school. Needless to say, the kids go wild.
- Super-Intelligence: The Krillitane oil gives people this if consumed. The chips/French fries the school staff are so insistent on the children eating are cooked with the stuff. It also rubs off on Rose because she was eating a lot of the chips.
- Tagalong Kid: Kenny, a chubby boy with glasses and unpopular amongst his classmates, is the only one not eating the chips due to a medical condition. This means he's the only one not put to work on the Skasis Paradigm and is left standing with the protagonists against the Krillitane. He does prove his worth by alerting Mickey to the situation so he and K9 can break in, and activating the fire alarm to stun the Krillitane's sensitive hearing. His reward for his efforts is the student body embracing him as cool for his role in saving the day (and crediting him with blowing up the school).
- Teachers Out of School: Subverted. When the main characters are sneaking around a suspicious school at night, Rose says that she used to think that teachers sleep at school. A moment later...
- Time Travel for Fun and Profit: The teacher the Doctor replaced resigned after winning the lottery... without playing. Someone posted the winning ticket through her door at midnight...
- To Serve Man: The Krillitanes eat students they can get away with killing, as well as the human teachers.
- Totally Radical: Parodied with "Correctamundo!", which the Doctor immediately swears off.
- Trailers Always Spoil: Sarah Jane's reappearance was spoiled by the trailer at the end of Christmas special "The Christmas Invasion"
- Unwanted False Faith: The Doctor is sorely tempted by the idea of gaining the power of the Skasis Paradigm.
- Utopia Justifies the Means: Mr. Finch exploits this in his attempt to recruit the Doctor: how many more people he could save if he were a Reality Warper?
- Villain Respect: Finch has a healthy respect for the Doctor's intellect, and he is the only character that Finch actually treats as an equal, even a superior; as part of his temptation of the Doctor, he says, "The paradigm would give us power, but you could give us wisdom." Of course, Finch is a top class Manipulative Bastard, so he might just be playing on the Doctor's ego. Either way, it almost works.
- We Can Rule Together: Mr. Finch gives the Doctor a sales pitch Mephistopheles would be proud of, and when Sarah Jane intervenes, shifts gears like lightning, pinpointing her own regrets and insecurities and offering her a similar sales pitch as part of the Doctor's.
- Wham Line: Mr. Finch catches the Doctor off-guard when, instead of planning to keep all the power for himself, he offers to share it with the Doctor:Mr. Finch: Think of the changes that could be made if this power was used for good.
The Doctor: What, by someone like you?
Mr. Finch: No. By someone like you.
- What the Hell, Hero?:
- Rose, to the Doctor, concerning him leaving Sarah Jane behind.
- Sarah Jane to the Doctor on the same subject, particularly for never coming back and leaving her to assume that he'd died.
- Who Wants to Live Forever?: This episode was the first time the series openly questioned why the Doctor leaves his companions (or lets them go):The Doctor: I don't age. I regenerate. But humans decay. You wither and you die. Imagine watching that happen to someone that you...
Rose: What, Doctor?
The Doctor: You can spend the rest of your life with me. But I can't spend the rest of mine with you. I have to live on, alone. That's the curse of the Time Lords.
- Would Hurt a Child: Finch devours a child at the beginning of the episode after first confirming that she has no parents who'll miss her. Wagner is also implied to kill one of his students for failing to crack the Skasis Paradigm.
- You Have Failed Me: Any student who doesn't measure up goes missing.
- Zeerust Canon: K9's dated look is lampshaded by Rose as "disco" (note that the character was introduced in 1977). The Doctor finds this very offensive.