In the Vortex, the TARDIS comes under a form of psychic attack resulting in the abductions of first Adric, then Tegan. Following their trail, the Doctor and Nyssa arrive under the lurid skies of the planet Zaltys, whose entire population has vanished in strange circumstances. Soon, they discover that Zaltys is now the target of treasure seekers, come to scavenge this so-called Planet of the Dead
Meanwhile, deep below the planets surface, Adric learns the earth-shattering reason why the people of Zaltys disappeared... and why they were wise to do so. And Tegan is, quite literally, in the dark enduring interrogation by the mysterious Clarimonde. Any friend of the Doctors is Clarimondes enemy... because theirs is a blood feud!
Zaltys contains examples of:
- Air-Vent Passageway: How Tegan and Lusca get away from the vampires.
- Bittersweet Ending: Zaltys is no longer in danger from the vampires and its people can come out of cryo-sleep at last, but outside of the TARDIS crew, Talia is the only major character to survive the story.
- Tegan cajoles Adric into trying to fly the TARDIS on his own by reminding him that he controlled it during "Castrovalva", though he reminds her he wasn't quite himself at the time.
- Tegan also thinks The Master was killed on Castrovalva. It won't be too long before she is proved wrong.
- Adric is reading "Dracula" as research in case they come across any more vampires.
- Chekhov's Gun: The ion bonder Tegan picks up from the TARDIS console comes in quite handy once she is transported onto the vampire ship.
- Disaster Scavengers: Sable's claim to fame.
- Evil All Along: Perrault.
- Fantastic Racism: Talia won't even shake hands with an alien, and is plainly disgusted at how many of them are suddenly on Zaltys.
- Fish People: Tegan's friend Lusca.
- Gevaudan taps Nyssa's psychic powers, which she and The Doctor are surprised she has. These will be seen again in "Time-Flight", and their origin uncovered in "Primeval".
- At the very end, The Doctor says of his companions that everything is perfect in threes. Adric then points out that, including The Doctor, that is actually four, making them one too many.
- Hunting the Most Dangerous Game: What Clarimonde and her vampires do to Tegan and Lusca.
- In the Back: This is how Talia dispatches Perrault.
- Meaningful Name: "Gevaudan" was the name of a French province in the 1760s that was supposedly terrorized by a man-eating wolf creature.
- Noodle Incident: Clarimonde seeks revenge against the Doctor for something he did to her people during his third incarnaton, while travelling with Jo.
- Reality Ensues: In-universe, Adric points out that even if Tegan did get back to Heathrow, there would be a lot of questions about her aunt Vanessa's "disappearance" that she wouldn't be able to answer. Tegan says she won't let that stop her.
- Shoot the Hostage: Sable threatens to do this to Nyssa, Tegan and Adric at separate points during the story, and it's made clear she isn't bluffing.
- Taking You with Me: Lusca drowns Sable, but not before Sable shoots her in the struggle.
- Trapped by Mountain Lions: Tegan is trapped on Clarimonde's ship and spends nearly the whole story fleeing vampires, completely unconnected from the main plot until the last few minutes. It's suspenseful enough that it still works.
- Our Vampires Are Different: They're called "necrobiologicals" for a start.
- Our Werewolves Are Different: They have psychic powers!
- Wolf Man: Gevaudan.