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Recap / Doctor Who S30 E5 "The Poison Sky"

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"You might as well have worn a T-shirt saying 'clone'... Although, maybe not in front of Captain Jack."
The Doctor

Original air date: May 3, 2008

The one where the Doctor has an in-joke with himself and Martha has a clone with a bald spot.

Written by Helen Raynor.

So the world's choking to death with Sontaran cloning gas spewing out of every car on the planet. UNIT gives the Doctor a gas mask (and ignores him when he quips "Are you my mummy?"). He hangs out with obvious-clone-Martha for a bit, because even though she's working for the Sontarans she happens to be doing exactly what he wants her to do: stop UNIT from launching a nuclear attack.

Rose very, very briefly shows up on the TARDIS's monitor screen, screaming at the Doctor. Donna doesn't notice.

Luckily, the Doctor can whip up something that can burn all the gas, cleansing the air, using technology that has conveniently been developed by Rattigan's geniuses for when they were going to move to a new planet. He also, once again, decides to sacrifice himself, but Rattigan takes his place and, in a Heroic Sacrifice, blows up the whole Sontaran fleet with a Sontar-HA!

As the Doctor and Donna prepare to see Martha off, the TARDIS abruptly takes off of her own volition, to an unknown destination...

Has a follow-up episode in the spin-off series The Sarah Jane Adventures called "The Last Sontaran".


  • Alas, Poor Villain: Martha clearly feels sorry for her dying clone, who really never had a chance for a life of her own.
  • Anger Born of Worry: After the Doctor's near-sacrifice, Martha immediately hugs him. Donna whacks him on the arm, then hugs him.
  • Apocalypse How: The Sontarans' Atmosphere Abuse threatens to at least cause a Class 2 that would force humanity to exist in specialised sealed environments (until the Sontarans eradicate the straggler pests from their new clone world, that is), and more than likely would actually cause an Class 5 for Earth's native life while the Sontarans come in and convert the planet's landscape into a breeding planet for themselves in the meantime.
  • Armour Is Useless: The Sontarans' armour, despite clearly looking bulkier than the standard UNIT armour, seems to be mostly decorative, as UNIT soldiers mow the Sontarans down when their firearms gain steel-cased bullets to avoid the Cordolaine signal. It might be that it's specifically designed to counter energy weapons, such as laser guns, in much the same way that Kevlar is specifically designed to stop bullets, not bladed weapons.
  • Artistic License – Gun Safety: The Doctor throwing Luke's gun across the room is incredibly dangerous, basically guaranteeing a misfire. That is, assuming the gun is even loaded.invoked
  • Atmosphere Abuse: The Doctor sets it on fire!
  • Atomic Hate: No Russia, for some reason. Even though North Korea gets in on the action!
  • Badass Army:
    • Subverted. The Sontarans appear to be one of these until UNIT overcomes their weapons being disabled and gives them the ass-kicking of the century. The Doctor had just introduced them as the greatest soldiers in the universe, too.note  Despite all their talk of discipline they fight as individual warriors, and once UNIT gets around their advanced technology (a field that makes copper-jacketed bullets unfireable), they're immediately cut down by UNIT's organized fire-teams. It's stated that they could have easily destroyed Earth from orbit without much trouble, but on the ground UNIT is more than equal to the challenge, especially since the Sontarans aren't expecting any resistance and allow themselves to be caught off-guard.
    • Played straight with UNIT, as once they find a way around the Sontarans' anti-gun field they proceed to mow down the Sontarans with ease.
  • Bad Guys Do the Dirty Work: The Sontarans correctly deduce that the Doctor is bluffing when he threatens to blow up their ship, reasoning that he doesn't have it in him to kill them all. As it turns out, Luke does.
  • Big Bad: General Staal, commander of the Sontaran forces at Earth.
  • Bizarre Alien Senses: The Doctor, apart from noticing various minor details about clone!Martha's appearance, can smell her being a clone.
  • Blue-and-Orange Morality: Commander Skorr seems genuinely pleased that Colonel Mace had the honour to demand he turn around before putting a few bullets into him, and compliments him on his martial virtue as he lays on the ground, dying.
  • The Brigadier:
    • Colonel Mace again carries on from the previous episode.
    • Brigadier Sir Alistair Gordon Lethbridge-Stewart himself also gets a Shout-Out. The Doctor says that he wishes the Brigadier was here. Mace agrees, compliments him and says that he's "stranded in Peru".
  • Chekhov's Gun: Chekhov's Hammer, in this case — Donna uses the one the Doctor occasionally uses on the TARDIS console.
  • Cliffhanger: As Martha's saying goodbye to the Doctor and Donna, the door slams shut and the TARDIS abruptly takes off of her own volition, startling everyone.
  • Cloning Blues: Martha's clone quickly falls into a downward spiral of it when Real!Martha's awakening cuts off her life support.
  • Colonel Badass: Colonel Mace proves he's one not only by inspiring UNIT to put some steel-jacketed rounds in Sontaran heads, but he also double-taps Commander Skorr with a pistol — this after Skorr easily took down two UNIT soldiers armed with automatic rifles, and Mace intentionally sacrifices the advantage of coming up behind him to look him in the eye.
    Colonel Mace: You will face me, sir!
  • Continuity Nod:
    • "Are you my mummy?"note 
    • The Valiant returns from the end of series 3.
    • The Doctor, who Donna can see and hear on a monitor, secretly communicates with her the same way he did with Mickey in a previous episode. He gets her attention by saying "noble", while with Mickey he repeatedly used the word "idiot" (which is what he frequently called him).
    • The whole Brig-stranded-in-Peru thing harkens back to the classic run and The Sarah Jane Adventures, where it's a Running Gag for the Brig to be "stranded in Geneva or Peru" when important things are happening with UNIT.
    • Rattigan calls the planet he intends to colonize "Earth.2", similarly to how the Cybermen referred to themselves as "Human.2".
    • The Doctor mentions Captain Jack to Martha's clone.
  • Cutting the Knot: While Donna and the Doctor try to fiddle with the car to unlock it, Donna's mother comes over and smashes the windscreen with an axe.
  • Deadpan Snarker: Colonel Mace learns this (not saluting) is the best way to cope with the Doctor's constant snide comments.
  • Deadly Gas: Downplayed — the gas is harmful, but not fatal until it reaches a very high density. This is a hint that it's not meant to be a weapon, but something else.
  • Defcon 5: Averted, the DEFCON status is used correctly. Nukes are ordered to be launched at Defcon 1.
  • Doesn't Like Guns: The Doctor gets extremely fed up with the excessive gun usage in this two-parter, to the point where he snatches Luke's gun out of his hand and throws it away without breaking his stride.
    The Doctor: (enters the Rattigan Academy via transport, Donna and Martha in tow) Here. The Rattigan Academy, owned by-
    (Luke enters, aiming a gun)
    Luke: (nervous) Don't tell anyone what I did. It wasn't my fault, the Sontarans lied to me, they-
    The Doctor: (walks past Luke while taking his gun; infuriated) If I see one more gun... (tosses gun away)
  • Don't Make Me Destroy You: The Doctor puts his own life at risk to give the Sontarans a chance to walk away. They're far too egocentric to surrender and decide it'll be worth it if he gets blown up with them.
  • Enemy Mine: The united nuclear response includes India, Pakistan, the USA, China and North Korea. (Oddly, not Russia.)
  • Failed Attempt at Drama: The Doctor gives Donna her own TARDIS key, echoing Rose and Martha. "Quite a big moment, really." Donna suggests they celebrate after dealing with the poison gas.
  • Fate Worse than Death: Luke's fellow students clearly consider his proposed "utopia" to be this; not even threatening them at gunpoint gets them to sign on.
    Luke: I designed a mating program. I planned the whole thing!
    Student: Well then, shoot me. [she leaves, as do the others]
  • Foreshadowing:
    • Brilliant but unnoticeable:
      Donna: [to Martha, who's wearing the Doctor's coat over her hospital-type gown] You know, that coat sort of works.
      Martha: Feel like a kid in my dad's clothes.
      Donna: Oh, well if you're calling him dad you’re definitely getting over him.
    • For a fraction of a second, Rose Tyler appears on the screen of the TARDIS when the Doctor sends his message to the Sontarans.
  • Forever War: The Doctor reveals that the Sontaran-Rutan war has been going on for fifty thousand years.
  • Freeze-Frame Bonus: Rose Tyler can briefly be seen on the TARDIS's screen, yelling the Doctor's name, before it switches to the UNIT control room; the Doctor doesn't see it as he's looking away from the screen at that exact moment.
  • Fun with Acronyms: ATMOS, again.
  • Gas Mask, Longcoat: The Doctor puts on a gas mask while wearing his Badass Longcoat.
  • Genius Breeding Act: Luke tells his fellow Teen Geniuses about the one he has planned. They don't respond enthusiastically.
  • Glory Seeker: The Sontarans would rather get blown up than let the Doctor win. In fact, getting blown up with the Doctor is even better! What a glorious death that would be!
  • Grammar Nazi: Luke and the whole "'Atmos System' is redundant because the S stands for System" thing returns hilariously. When the Sontarans reveal that they'd have used Luke and his students as target practice once they'd outlived their usefulness, they don't actually make a priority of doing anything to the lone Luke... until he corrects them about that again. Then it's "EXECUTE HIM!"
  • Gunship Rescue: "UNIT carrier ship Valiant reporting for duty, Doctor." Despite his usual dislike of weapons and soldiers, the Doctor is genuinely impressed, and, before he catches himself, excited. Cue Colonel Mace's pointed remark.
  • Heel–Face Turn: Rattigan rescues the Doctor from his own Heroic Suicide so he can finish off the Sontarans himself.
    • Martha uses their shared memories to convince Clone Martha to betray the Sontarans and tell her the composition of their gas mixture. Unfortunately, with Martha disconnected the clone is dying, so this is her last act.
  • He Had a Name: "He wasn't 'Greyhound 40', his name was Ross. Now listen to me, and GET THEM OUT OF THERE!"
  • Heroic Sacrifice: Luke "does something clever" by swapping himself with the Doctor and blowing up the Sontarans and himself.
  • "Hey, You!" Haymaker: Colonel Mace does this to Commander Skorr — with his gun.
    Mace: You will face me, sir!
  • Honour Before Reason: Both the Doctor and Colonel Mace.
    • Mace challenging Commander Skorr rather than just double-tapping him from behind. Since Mace is a Colonel Badass, he still puts Skorr down.
      "You will face me, sir!"
    • The Doctor's doesn't quite go as well.
      Martha: Just send that thing up on its own. I don't know, put it on a delay!
      The Doctor: I can't.
      Donna: Why not?
      The Doctor: I've gotta give them a choice.
  • Hostile Terraforming: Weakened by their eternal war with another race of Scary Dogmatic Aliens, the Sontarans hatch an uncharacteristically circuitous plan to bathe the Earth in gas which is poisonous to native life but nutritious to themselves, so that they can use it to spawn more soldiers.
  • Hyper-Awareness: The Doctor can tell that the Martha shadowing him all episode is a clone because of "reduced iris contraction", and a "thinning of the hair follicles on the left temple".
  • Idiot Ball:
    • Donna. Possibly justified because she is alone in a dangerous situation (and thus may not be thinking as clearly).
      Donna: [on phone to the Doctor, regarding the use of a door switch] But it's Sontaran-shaped, you need three fingers!
      The Doctor: ... You've got three fingers.
      Donna: Oh yeah!
    • Despite knowing about the Sontarans' gun-blocking signal, the Doctor doesn't tell the Colonel, resulting in Ross's untimely demise.
  • Informed Ability: The Sontarans being the "universe's greatest soldiers" when their tactics appear to mostly consist of walking forward and shooting people. Sure they mopped the floor with the UNIT forces in the first encounter, but once the humans got past the Sontarans' blatant cheating (a field which prevented their weapons from firing, making them incapable of even fighting back) they absolutely kerb-stomped the "invincible" Sontarans. And unlike, say, Daleks with powerful shields, these guys get cut down by bullets pretty easily when their copper-expanding gimmick fails.
    • Considering this is coming from a Technical Pacifist who views the word "soldier" as an insult, and that Sontarans are obviously a Martyrdom Culture that believes War Is Glorious, this actually may have been a bit of Fridge Brilliance. And it was stated several times throughout the episode that the Sontarans were holding back since they could have killed everyone easily, but needed the planet intact; and the Sontarans inside the factory were caught flat-footed, as they expected no resistance since the soldiers' weapons were disabled.invoked
  • Insufferable Genius: Luke Rattigan is revealed to be a Jerkass Woobie because of this. All he ever really wanted was to have some real friends who would praise him for his achievements, hence why he was so willing to work for the Sontarans, even hoping they'd adopt him into the fold, as it were. When they reveal he's disposable, he takes the Doctor's comment that he should do something clever with his life to its logical conclusion and decides to atone for his error by doing a Taking You with Me to the Sontaran mothership. invoked
  • In the Back: Colonel Mace defies it, but only just. Coming up behind Commander Skorr during the UNIT counterattack, he bellows, "You will face me, sir!" and then puts three bullets in Skorr's chest the second he turns around.
  • Intelligence Equals Isolation: Invoked by Rattigan, who argues that he and his fellow geniuses have spent their lives being excluded and laughed at by other people, and thus deserve to live more than "those cattle". Unfortunately for him, no one else thinks that way: his fellow students turn out to be quite well-adjusted and just want to find their parents. Rattigan is reduced to impotently ranting that this "proves" he's cleverer than them.
  • It Has Been an Honour: "Donna, thank you. For everything. Martha, you too. Oh, so many times. Luke, do something clever with your life."
  • Just Between You and Me: Defied: "A general would be unwise to reveal his strategy to the opposing party."
  • Kerb-Stomp Battle: The Sontarans find themselves on the receiving end of one this time once UNIT figures the Sontaran technology that stops their guns from firing. Once that happens, the aliens start getting mowed down.
  • Kick the Dog: When Donna and Sylvia talk on the phone, Donna tries to reassure her mother that people are working on the gas problem. Sylvia just snidely asks how she'd know that.
  • Know-Nothing Know-It-All: A rare instance of the Doctor being one of these; he furiously insists to Colonel Mace that "you can't! Fight! Sontarans!", only for Mace to dismiss his concerns and give a Rousing Speech to his men while the Doctor rolls his eyes. Mace then entirely subverts the expected pointless and avoidable slaughter of his men in a futile attack when UNIT slaughter the overconfident Sontarans, with Mace personally gunning down their ground commander, making the Doctor's warning come across as borderline hysterical.
  • Leaning on the Fourth Wall: When the Doctor complains about being stuck on Earth like a human, he quickly apologizes. As he does that, he looks at the camera for long enough that this apology is more to the viewers than (evil) Martha.
  • Martyrdom Culture: The Sontarans.
    The Doctor: General Staal, you know what this is. But there's one more option: you can go. Just leave. Sontaran High Command need never know what happened here.
    Staal: Your stratagem would be wise if Sontarans feared death, but we do not.
    • However, this doesn't stop them having an Oh, Crap! moment when Luke replaces the Doctor — because they know that A) unlike the Doctor, he won't hesitate, and B) they've just lost the chance to take the Doctor down with them. Also, C) they could just be surprised that Luke of all people showed up.
  • Mauve Shirt: After spending 1.5 episodes as the Doctor's sidekick, Ross Jenkins is killed in battle. This is why the Doctor doesn't like guns!
  • Monumental Damage: Though they aren't damaged, news reports show poison gas around the Hagia Sophia and the Sydney Opera House. Also, the ignition of the gas in the atmosphere sweeps over the Chrysler Building in New York.
  • More Expendable Than You: Luke sacrifices himself in place of the Doctor to blow up the Sontaran ship.
  • Mundane Solution: When they find out the Sontaran technobabble field affects the copper in their bullet casings, UNIT just switches to steel-cased ammo and goes to town.
  • Mythology Gag: In New York, one of the buildings has a name reading "Butler Institute". The Butler Institute was a sinister Enigmatic Institute in the Virgin New Adventures book Cat's Cradle: Warhead.
  • Never My Fault: Luke, pointing a gun at our heroes, demands they not tell anyone what he did. "It wasn't my fault, the Sontarans lied to me!" The Doctor snatches the gun and throws it away without slowing down.
  • Newscaster Cameo: Newsreader and presenter Kirsty Wark.
  • No Endor Holocaust: How the Doctor managed to ignite the lower level of the planet's atmosphere without frying or baking the people and living things on the planet underneath the global-scale explosion is anyone's guess. Or manages to avoid destroying it and/or the ozone layer.
  • The Nose Knows: Clone Martha apparently smells bad, but only the Doctor can tell.
  • Not Herself: Martha. The Doctor suspects this almost immediately — one of the first things he asks the clone is if she's called her family. "No, what for?" Also, she smells.
  • Officer and a Gentleman: Colonel Mace, who on spotting Commander Skorr, barks "You will face me, sir!", and waits for him to turn (though only just) before shooting him.
  • Oh, Crap!: The Sontarans, when they see that Rattigan has replaced the Doctor.
  • Out-Gambitted: The Martha clone prevents UNIT from launching nuclear weapons at the Sontarans, only to discover that's just what the Doctor wanted, having immediately recognized her as a fake. As the Doctor points out, she's essentially an unwitting triple-agent.
  • Out-of-Character Alert: The clone of Martha has the original's memories, but not her concern for her family. She also misses the Doctor going "Avanti" instead of "allons-y", and gives off several other tells to an alien with Hyper-Awareness.
  • Pendulum War: The conflict. At first UNIT is routed because the Sontarans have made their weapons inoperable. When UNIT brings in new bullets that aren't affected by the Sontaran technology, they return the favour.
  • Proud Warrior Race Guy:
    Skorr: [dying] Wonderful...
  • Rank Scales with Asskicking: Colonel Mace can kill a Sontaran — Commander Skorr, no less, who's an example in his own right — in one shot without using the back of the neck weakness. No one else can do this. Oh, and he warns the Sontaran of his presence.
    "You will face me, sir!"
  • Red Sky, Take Warning: This one is burning with a global fire.
  • Redemption Equals Death: Luke Rattigan commits suicide, saves the Doctor, and destroys the aliens when he realises how badly he screwed up.
  • Redshirt Army: Zigzagged with the UNIT troops. Initially the Sontarans slaughter them with their laser guns, because the troops are defenseless against them as the Sontarans' "Cordolaine Signal" renders UNIT's firearms inoperable. As soon as Mace is informed of the bullet issues, they switch ammunition to steel casing bullets (which avoids the problem of copper bullet expansion blocking the barrel), after which, they then goes back in and they mop the floor with them, meaning the Sontarans become this.
  • Rousing Speech:
    • Mace gives one to his soldiers about how they're going show the aliens that they are not Puny Earthlings. The mocking laughter stops now! The result is a highly motivated fighting force.
    • Rattigan attempts to give one to his Academy geniuses about how Earth doesn't appreciate them and how they can leave it behind to start again! The result is everyone walking out on him.
  • Screw This, I'm Outta Here: Rattigan's students abandon him when he reveals his part in the Sontarans' invasion and his plans for how they can all survive on a new world.
  • Shout-Out:
  • Shut Up, Kirk!: A rare heroic example: "Thank you, Doctor, for your lack of faith, but unfortunately I've stopped listening." After two episodes of contempt and insults from the Doctor, whom he had treated with utter respect from the start, Colonel Mace finally stops listening and proceeds to prove the Doctor wrong and wipe the floor with the so-called "universe's greatest soldiers". However, the mothership would have wiped them out from space if it wasn't for a mixture of the Sontarans being Blood Knights and wanting to have fun on the ground, and the Doctor, so he was correct about them standing no chance against the Sontarans. On the other hand, the Doctor doesn't seem to have any idea how to get rid of the Sontarans on the ground himself, and his plan to destroy the mothership would have been an Epic Fail if not for Luke making the hard choice for him, so he definitely needed UNIT's assistance. Notably, while the Doctor never congratulates Mace on the bullets thing (though this being the Doctor he wouldn't) he flat-out congratulates Mace for the use of the Valiant, being genuinely impressed.
  • Smooch of Victory: Captain Price plants one on Colonel Mace when the wave of fire caused by the atmospheric converter passes to reveal a clean blue sky. They then get right back to business.
  • Soldier vs. Warrior: UNIT fights like soldiers in organized squads, the Sontarans fight like individual warriors — and UNIT are much more mobile. The Sontarans didn't stand a chance once their bullet-inhibiting field was disabled.
  • Squick: In-Universe, as disgusted as Rattigan's fellow students are by his plan to destroy the Earth and move the school off-planet, what ends up making them leave is that he planned a mating program for them. (What's worse is that you'd need at least 200 people to repopulate humanity without a lot of incest, and there are nowhere near 200 students at Rattigan's academy. Bit of Fridge Brilliance there, since most likely at least one of the genii knows that).
  • Stuff Blowing Up: The Doctor lights the upper atmosphere on fire. If the crossed fingers and "Please, please..." muttering are any indicator, the Doctor wasn't sure it wouldn't destroy the Earth.
  • Swap Teleportation: Luke Rattigan pulls a Redemption Equals Death by switching places with the Doctor using one of these, taking his place in the Suicide Mission to stop the Sontarans. This is how he chooses to interpret the Doctor's parting instruction to "Do something clever with your life."
  • Taking You with Me: The Sontarans consider their deaths acceptable if they get to take the Doctor down with them. They have five seconds to reconsider when Luke takes his place.
    The Doctor: You'll die, Staal!
    Staal: Knowing that you die, too.
  • Tempting Fate: Martha really should have said her goodbyes and "I'm good here" stuff outside the TARDIS. In fairness, she had no way of knowing what would happen.
  • Twin Threesome Fantasy: Discussed; the Doctor tells the Martha clone that she'd best not wear a T-shirt saying "Clone" in front of Captain Jack Harkness.
  • Undressing the Unconscious: The real Martha wakes up barefoot and wearing only a Modesty Bedsheet, having been stripped of her clothes in the previous episode to disguise her evil clone.
  • Unwitting Pawn: The Martha clone doesn't realize that the Doctor rumbled her a good while ago, but like the Sontarans he also wants her to keep cancelling the weapons launch. Furthermore, he deliberately tells Mace that he's going to use the TARDIS to get onboard the Sontaran ship within Clone Martha's hearing, leading her to thwart him by having the TARDIS teleported onto the ship while unbeknownst to her, Donna is onboard.
  • World-Healing Wave: Setting the sky on fire to remove the poison.
  • You Are Better Than You Think You Are: The Doctor to Donna when she thinks she can't be helpful.
  • You Have Outlived Your Usefulness: The Sontarans execute the brainwashed human soldiers, and were planning to use Luke and his students as target practice.
  • You Must Be Cold: The Doctor gives Martha his coat. It's a bit big for her, but Donna thinks it works.