The story starts out with the Daleks wiping out a fleet, hospital ships included. They can't put up a fight at all, and the Daleks show no mercy because all humans are the Enemy of the Daleks. Only one small ship escapes.
The Doctor, Ace and Hex land on a planet called Bliss, which is supposed to be a paradise planet, but it's overgrown in non-native flora. And those humans in the previous paragraph land, with the Daleks on their tail.
One last stand, and the Doctor is caught in between horrible creations that might spell the end of the universe, and the Daleks.
- Always a Bigger Fish: That horde of Piranha Locusts? Wait till they meet the Daleks.
- That fleet of Daleks? Wait till they meet the Kiseibya.
- Amazon Brigade: The Valkyrie Unit consists completely out of women to fight Earth's biggest enemy.
- Bavarian Fire Drill: The Doctor gets the trio into a safe compound this way, and he even admits he's making things up in the conversation.
- Better to Die than Be Killed: The Black Dalek implores the Doctor to overload his power cells, thereby creating a localized explosion, over being eaten alive.
- Two leftover Daleks as well, chose to exterminate each other over becoming carriers for the Kiseibya.
- Body Horror: Kiseibya, like certain species of wasps, lay their eggs in living organisms. Like Daleks.
- Call-Back: Hex compares the Daleks (who he hasn't met yet) to the Cybermen.
- The Daleks employ the concept of Rels again.
- Ace mentions she's "Had her moments" in fighting Daleks.
- The Doctor recounts this isn't the first time he had to commit genocide.
- Dalek replicants have been around for a while.
- Ceiling Cling: Kiseibya can do this.
- Colour-Coded for Your Convenience: There is a Black Dalek as the leader. Later, the Doctor and Professor Toshio recognize a Kiseibeya by the fact its shell is darker, and therefore older.
- Cold Open: A Dalek ship wiping out the larger part of a Generation Ship fleet.
- Crisis Point Hospital: The research base's infirmary at first appears to be functioning perfectly - up until you notice the locked ward for victims of the recent viral outbreak: unable to treat these patients, the Sistermatic medical droid has been forced to simply leave them there under strict quarantine. By the time the Doctor arrives, the base personnel are all dead or dying with the exception of Professor Shimura, and most of the bodies have been dumped outside in a mass grave. It turns out that the "virus" is a hoax: Professor Shimura has been using his research staff as hosts for Kiseibya larvae, and is keeping his surviving ex-colleagues under lock and key while the larvae slowly eat them alive.
- Death Seeker: Lieutenant Beth Stokes.
- Defiant to the End:Stokes: They crashed the wrong party! You hungry!? EAT THIS!
- Eaten Alive: Several Daleks. Casing and all.
- Eat Dirt, Cheap: The Kiseibya that the Professor Toshio bred from the Piranha Locusts devour their weight in metal upon emerging from their cocoon.
- Heroic Sacrifice: Stokes does this, unfortunately after she's found a new will to live.
- His Quirk Lives On: After killing his creator, the first spawned Kiseibya starts humming the lullaby.
- Horde of Alien Locusts: Piranha Locusts on the planet Bliss. They're even 5 times bigger than they normally are, making them extra lethal.
- I Did What I Had to Do: Professor Toshio engineered the Kiseibya to destroy the Daleks. Them feeding on human flesh was ... necessary.
- Ironic Echo:Black Dalek: MER-CY.The Doctor: I thought you had no need for mercy.
- Later on
Kiseibya: You recognize me?Professor Toshio: You recognize me? - Japanese Ranguage: Professor Toshio has issues with his L's and R's. It's not played for comedy, and the voice actor is born in Japan to avoid
Unfortunate Implications. - Leit Motif: The space troopers have one that rocks and give them a hasted, chased feel to their commands and actions.
- Meaningful Name: Kiseibya is a Portmanteau of "Parasite" and "Saviour" in Japanese.
- Mistaken for Disease: The research facility has supposedly been struck by a mysterious disease, infecting almost the entire staff population and forcing Sistermatic to quarantine them while they slowly die. The only survivor is Professor Shimura, who claims to possess natural immunity. As it turns out, the "disease" is actually a parasitic infestation: Shimura is using the staff as incubators for the larvae of his genetically-engineered Kiseibya, which are now literally eating the researchers alive. For good measure, Sistermatic has been sabotaged so as not to recognize this fact, being unable to explain the condition of the patients even when Hex points out that infections don't leave bite marks.
- Mistaken for Spies: When the Doctor, Ace and Hex are on the run from the Piranha Locusts the troopers think they might be Dalek replicants.
- Names to Run Away from Really Fast:The Doctor: Piranha Locusts.Hex: Not exactly a name that inspires confidence.
- Non-Indicative Name: Bliss, nowadays.
- Parasites Are Evil: Created as a biological weapon for use in the war against the Daleks, they are voracious parasitoids in their larval stage, slowly and painfully devouring their hosts from the inside before metamorphosing into metal-eating adults. They're found to be intelligent enough to speak, but possessed of an outlook that's nothing short of terrifying: if they were deprived of Daleks to prey on for food and incubation, they'd gladly turn on humanity. After seeing the Kiseibya disable the Black Dalek and implant him with their eggs, the Doctor decides that they can't be allowed to leave their home world...
- Pupating Peril: Zig-zagged. Though the emergence of the first Kiseibya is played for horror, complete with Shimura forcing the Doctor to kneel before it as it hatches, the threat turns out to be non-existent: adult Kiseibya live exclusively on metal - and only become a threat to organic life when it's time for them to breed. However, it's played very straight when the Daleks find the now-empty cocoons... just in time for the entire swarm to ambush them.
- The Professor: Professor Toshio Shimura.
- Safely Secluded Science Center: Roark 359, a laboratory complex hidden away on the Paradise Planet of Bliss. Not only is this place the only settlement on the entire planet, but the facility's been partially evacuated due to the ongoing Dalek war, and the rest have been gradually picked off by the "plague."
- Shell-Shocked Veteran: Lieutenant Beth Stokes would rather die than be imprisoned in a Dalek camp.
- Songs in the Key of Lock: Sistermatic the Robot Buddy to the professor has a password based on a song. The song has to be in key too.
- Summon Bigger Fish: Professor Toshio purposefully employs this trope.
- The Swarm: Again, the Piranha Locusts. Later the Kiseibya.
- Tuneless Song of Madness: The realization that she's going to be captured alive breaks what little remains of Beth Stokes' sanity, and she's later found cowering in the kitchen, singing a lullaby.
