The one where Susan stabs a mattress.
One of Doctor Who's few Bottle Episodes, "The Edge of Destruction" (a.k.a. "Inside the Spaceship") is a two-part oddity wedged between two longer stories. Originally, the show was confirmed for four episodes (the opening story) to be reviewed up... then it was increased to 13, two more than "The Daleks" allowed for. Worse, there was no money for sets or extras. Although it's a filler episode, the story triggers some very important Character Development for the Doctor and his friendship with Barbara.
The TARDIS lurches and everyone falls over, and when they get back up again, everyone's acting a bit odd. Weird stuff starts happening and the Doctor suspects there's an alien presence on board and gets very paranoid. He accuses Ian and Barbara of sabotage, drugs their cocoa, and is himself attacked by Susan running with scissors.
Turns out it's the TARDIS itself that's the problem. The Doctor hit the Fast Return Switch at the end of "The Daleks", but it got stuck and the TARDIS has been whizzing back in time to the creation of the Universe... and, therefore, destruction. The weird stuff was the ship trying to warn its crew, who fix the problem (a faulty spring; lovely 1960s space technology) and go on their way. The Doctor apologises to Barbara for having been an utter git to her, and acknowledges that she saved their lives by realising the TARDIS was talking to them all along.
- A House Divided: The main characters are stuck in the TARDIS. Outside, the ship is about to tear itself apart and inside they're at each other's throats.
- The Alleged Car: All this arc's problems are caused by a stuck button and broken spring. As the show reveals later, this module was a museum piece when the Doctor was still a young man.
- Billions of Buttons: The console's (as iconic to Doctor Who as the blue police box) caused the actors to start labeling them.◊Incidentally, on the DVDs it turns out that nobody is sure who actually wrote it. Carole Ann Ford suggests it may have been her and Hartnell during rehearsal, but she isn't sure.
- Bottle Episode: The entire story takes place in the TARDIS and its functions are shutting down, so a minimalist thing. The production crew likely needed a bottle episode at this point due to problems with the first two serials, including the first episode of each needing to be redone due to problems.
- Break the Haughty: Given that the Doctor was well into the "vicious" side of Anti-Hero in the first two stories, his behaviour here isn't very surprising. However, he reaches a new low upon threatening to throw Ian and Barbara out the TARDIS, something that could easily kill them. When the woman he threatens to kill not only gives him one hell of a What the Hell, Hero? but also figures out the problem and saves the day, the Doctor is understandably humbled. Not only does this lead to his attitude improving but sets his moral compass in a more unambiguously good direction, something that determines the show's outlook to this day.
- Character Development:
- This episode is a major stepping stone in having the Doctor's personality be more like what we know today rather than the Jerkass seen previously.
- This story begins developing the TARDIS, the first story to even hint at it being autonomous. Before this, it was mostly treated as any other time machine/spaceship; after this, writers and serials would hint more and more at it being alive, before finally being confirmed in "The Doctor's Wife".
- Early Installment Weirdness:
- Ian checks the Doctor's heartbeat and only hears a single beat. It's later established that the Doctor has two hearts.
- The Doctor scoffs at the idea that the TARDIS is sentient. The modern series in particular ran with this concept.
- However, considering the Doctor concedes that the TARDIS does possess a "machine intelligence" due to its many computers, and it's eventually revealed that the TARDIS is communicating with the group, this episode can easily be read as the moment where the Doctor realized just how intelligent the TARDIS really is. It's still a pretty far cry from the TARDIS having "a heart and soul" that manifests as glowy yellow light and is sentient enough to manifest in humanoid form, though.
- Continuity Nod: As Barbara is chewing out the Doctor, she mentions the events of the previous serials.
- Easy Amnesia: Temporary amnesia affects the crew as they forgot one another.
- Eldritch Location: The TARDIS itself becomes one. This was the first hint that the ship might be alive.
- Everybody Lives: No explosions and no stabbing means no death.
- Family-Unfriendly Violence: The scene in which a strung-out Susan threatens the other characters with a pair of scissors and ends up frenziedly stabbing a mattress (see the still photo above) sparked the first of the many controversies about whether Doctor Who was too violent/frightening.
- Foreshadowing: That Susan would be the most affected by the malfunctioning TARDIS makes a lot of sense after the latter revelation of her having above-average (even by Gallifreyan standards), but far from fully trained/controlled psychic abilities.
- Midair Repair: The Doctor has to fix the TARDIS before it hits the Big Bang and is destroyed.
- Mind Screw: It's a baffling adventure inside the ship today.
- Minimalist Cast: Only the four crewmembers and the TARDIS herself.
- My God, What Have I Done?: The Doctor's been a bit of an ass until this point in time (and space), including threatening to bludgeon a caveman to death because he would've held the TARDIS crew up. But he has an epiphany at the end of this story on what a Jerkass he's been, and loosens up and becomes the Doctor we all love and know.
- No Antagonist: Unless a faulty spring counts, there is no bad guy here. Interestingly enough, this is probably one of the only instances that the Doctor himself could be argued as one.
- Noodle Incident: Susan recognises a photograph on the screen as Quinnis, a planet in the fourth universe where they nearly lost the TARDIS. As revealed in the Big Finish story "Quinnis", it was almost carried away by a flood when the Doctor was posing as a rainmaker.
- Not Themselves
- Nothing Is Scarier:
- There's no clear enemy for the first episode, with the malevolent presence represented by the TARDIS doors opening and closing and everyone on the ship going slightly mad thanks to its psychic influence. The second episode of the serial shows them actually puzzling through the problem and isn't half as scary, but the first episode is just horrifying.
- The Doctor and his companions are trapped inside the TARDIS, which is stalled in the Void, while everything is both broken and working at the same time...while Susan screams about something having gotten inside the TARDIS and trying to kill one of the other companions with a pair of scissors.
- Reality Ensues: The story shows how scary and dangerous it can be living in an alien ship that is apparently alive, is broken and which the Doctor doesn't entirely understand how to work, which is usually Played for Laughs. A minor fault on the console almost destroys the TARDIS by throwing it back through time towards the creation of a galaxy and the TARDIS's attempts to warn the crew leave them confused and scared something else is inside the ship.
- "The Reason You Suck" Speech: Barbara gives the Doctor a big lecture about how he cares nothing about anyone else, thinks that he is the most important person in the universe, has no sense of right and wrong, just does whatever he wants to all the time even if it endangers other people, and is a horrible man, a terrible grandfather and genuinely deserves to be dead. This leaves him quite shaken, and the final part of the serial shows him apologizing to her for his behaviour and admitting that her spirit in calling him out on it is the same thing that caused her to figure out what was wrong with the TARDIS and how to save them all. This is very important in giving him Character Development.
- Reset Button: AKA The Fast Return Switch. This was the first and only time it was ever mentioned and it isn't working.
- Sinking Ship Scenario: This ship is malfunctioning and about to disintegrate.
- Slipping a Mickey: The Doctor drugs Barbara and Ian's drinks to knock them out so he can investigate what is happening to the TARDIS without interference. Ian doesn't fall for it, however.
- Unbuilt Trope: This story is an absurdly dark look at how miserable and paranoid it would be to be unworldly humans living aboard a Sapient Ship that travels semi-autonomously across time and space with a mysterious alien at the helm – by this point, Ian and Barbara's hatred of the Doctor is enough that both think the other may have tried to murder him (and they did not choose to be his companions either, instead being kidnapped by him), the Doctor hates Ian and Barbara for being human interlopers who may be trying to steal or hurt his ship, and Susan, while appearing to be The Ingenue, is just as inscrutable and alien as her grandfather and has a violent mental breakdown, babbling about creatures living inside her, and attacking Ian with a pair of surgical scissors. During all of this, they are dealing with a Negative Space Wedgie, the effects of which are so unlike anything that they have seen before that they constantly wonder if this is actually a malevolent force or something the TARDIS, which has a mind of its own impossible to understand outside of its species, is doing for their sake. Another aspect is that the TARDIS being unreliable and the Doctor being unable to control it is usually portrayed comically. However this serial shows how dangerous it could really be when the TARDIS goes wrong, here a spring coming loose on the console nearly destroys the ship by throwing it back in time to the creation of a galaxy.
- What the Hell, Hero?: Barbara Wright gets a great one. The Doctor is threatening to throw her and Ian out of the TARDIS, into empty space, and she tells him he has no right to threaten them as he owes his life to the two of them several times over already.
- Barbara: How dare you! Do you realise, you stupid old man, that you'd have died in the Cave of Skulls if Ian hadn't made fire for you? And what about what we went through against the Daleks? Not just for us, but for you and Susan too. And all because you tricked us into going down to the city. Accuse us? You ought to go down on your hands and knees and thank us. But gratitude's the last thing you'll ever have, or any sort of common sense either.
- The World Is Just Awesome: At the end, the Doctor delivers a truly beautiful speech on the creation of a solar system.We're at the very beginning, the new start of a solar system. Outside, the atoms are rushing towards each other. Fusing, coagulating, until minute little collections of matter are created. And so the process goes on, and on until dust is formed. Dust then becomes solid entity. A new birth, of a sun and its planets.
- The X of Y: The firstnote of a long, Long, LONG line of such titles.