As Frobisher and Peri rummage through the TARDIS storage, the Doctor informs them that the ship has been infiltrated. Peri and Frobisher's attempts to help him investigate do not go well, and they get separated. Peri finds the Doctor in one of the gardens... while Frobisher finds the Doctor somewhere else. The Doctor with Frobisher quickly realised that what he thought was a swuffle in the TARDIS zoo was actually a shapeshifter, a Kymbra Chimera, and the "Doctor" Peri met looms behind her...
The Doctor and Frobisher then track Peri and the shapeshifter to the old secondary control room. Luckily, Frobisher can tell the real Peri from the fake, and the Doctor ejects it into space.
Tropes:
- Continuity Cavalcade: The Doctor keeps his fourth and fifth selves' outfits on mannequins, and has Bessie in a store room.
- Shapeshifter Showdown: Frobisher (whose chronic monomorphia is better again) engages the Chimera to distract it until the Doctor can eject it.
- Spot the Impostor: The Doctor and Frobisher are confronted with two Peris. Luckily, Frobisher knows exactly what to look for and spots the Kymbra Chimera immediately.
