The ruthless hunter Sebastiene decides to hunt the Doctor and brings together a team of hunters, the Endangered Dangerous Species Society. The Tenth Doctor and Donna are caught up in his trap.
- Continuity Nod: Donna, on seeing the TARDIS has brought them to a snowy area, mentions the Ood planet.
- Sebastiene tells the Doctor he should try snaring a Dalek or Osiran.
- Among Sebastiene's trophies the Doctor sees a Raston Warrior Robot and a Wirrn.
- The Carpalian Witch's previous biggest catch was a Sontaran.
- Sebastiene mentions that the Doctor was quiet for a while, probably both referring to the Time War and the time when Doctor Who was off-air.
- The Dreaded: The Doctor to the EDSS. With good reason, as it turns out.
- Egomaniac Hunter: Sebastiene. And the other members of the Society.
- Foreshadowing: Brutus telling the EDSS the Doctor will destroy them all.
- Gambit Pileup: The Doctor brainwashed Baris and took his place. Sebastiene knows that the Doctor has a plan, but can't figure out what it is. Eventually, he does figure out that "Baris" is up to something, but his own Complexity Addiction keeps him from realizing the obvious truth, along with the fact that the Doctor knows Sebastiene knows he's up to something, but plays Obfuscating Stupidity up to eleven. At one point, the Doctor's Chronic Hero Syndrome nearly gets him killed, but he actually tells Sebastiene that it's all part of "the Doctor's" plan. And then the hunters all start trying to kill each other and the Doctor or rather, Baris...
- Loony Fan: Baris, the Doctor's number one fan. He has had Mega Plastic Surgery to look like him, sound like him and have a second heart fitted.
- A critical misunderstanding on Sebastiane’s part about Baris’ obsession with the Doctor makes him assume that Baris will be perfectly happy to Kill and Replace his Idol. Instead Baris’ obsession with the Doctor means that he wants to truly “be” the Doctor and that means that he tries his best to embody the standards that the Doctor does, as well as his morals.
- Reality Warper: Sebastiane appears to be able to do this on Planet 1, the atmosphere is saturated with Intelligent Molecular Technology that enables him to conjure up anything he wants with a wave of his hand.
- Spider People: The Carpalian Witch.
- Straw Fan: Baris spends all his time online with other fans talking about the Doctor's adventures. That's definitely not a subtle jab at all the Doctor Who fans on social media.
- Too Dumb to Live: Brutus the augmented Simian, who tells Sebastiene there can only be 12 members of the Society. This is lampshaded when Sebastiene inwardly marvels at this stupidity. Sure enough, Brutus is incinerated when he tries to leave.
