The Doctor, Mel and Ace land on Earth in the future, where the Earth has been divided into two halves: The East and West blocs and an attempted nuclear attack the previous year is fresh in the minds of the locals. Upon exploring a cave system, the trio discover an enclave of Silurians who want to finish what they couldn't the previous year: the extinction of humanity.
Tropes
- Bait-and-Switch: When the Doctor states "...so anyway, I dispersed the Key to Time throughout the universe so the Black Guardian couldn't get his hands on it again", we assume he was describing to Ace his entire life story during a particularly boring elevator ride. It turns out, it was literally the first thing the Doctor said to Ace in 20 minutes, as he had forgotten she's not telepathic and he was describing his life story in his head.
- Brainwashed and Crazy:Falco: I'm not mad, just brainwashed!
- Call-Back: Ace mentions that the Doctor's "quick stops" on Earth typically involve super-weapons he's discarded there like "the Foot of Omega".
- Mel says the only time The Doctor kept a secret to himself was when they were travelling in Pompeii.
- The Silurians say their name is a misnomer, and refer to themselves as Homo Reptillians. The incorrect name had previously been pointed out by the Doctor himself.
- Call-Forward: When he's knocked out, The Doctor says he had a terrible dream of a man in ringlets entering a room The Doctor was waiting and telling him his time's up.
- The Doctor's apparent ownership over Earth is later recognised by the world's governments.
- Continuity Nod: When Chordok tells Avoxx his plans on wiping out the humans, she repeatedly tells him there's got to be a better way (to avoid bloodshed), which is a reference to the Fifth Doctor's last line in Warriors Of The Deep.
- Expospeak Gag: The Silurians describe the Doctor's umbrella as "a tool providing protection against precipitation".
- Manchurian Agent: Chairman Falco.
- People in Rubber Suits: In reference to the somewhat unconvincing monster costumes used in Classic Doctor Who, Mel initially thinks the Silurians are actually people in costume.
- Robot Buddy: The Doctor calls the Carlas this.
- Secret Passage: Ace thinks the island's library has one. She's right.
- Sequel: To "Warriors of the Deep".
- Shout-Out: Mel says The Doctor reminds her of Willy Wonka.
- The title is an obvious one to The Manchurian Candidate.
- Take Over the World: The Doctor reveals that after saving an important alien in a previous story, he was gifted the legal ownership of Earth. As a result, he spends most of the story apparently trying to give it back to the Silurians, to Ace's disgust. Whether it's true or not isn't clarified.
- Title Drop: After Melanie says she travels with The Doctor and so she expects the impossible, Ruth replies with "Doctor Who?"
- A True Story in My Universe: The Doctor says that Edgar Rice Burroughs knew the Silurian capital city as "Pellucidar", implying it inspired Burroughs's titular series.
- You Have Researched Breathing: The Doctor and Ruth get frustrated when they discover that Carla doesn't have a whisper function, only Platinum Carlas have it. As a result, their cover is blown.
