The TARDIS materialises on the runway of Gatwick Airport, where Polly witnesses a murder only to be kidnapped before she can report it.

When Spencer attempts to kill them, the Doctor, Jamie and Sam become convinced Chameleon Tours are hiding something and Sam decides to book a ticket on one of their flights.

Jamie finds himself aboard the Chameleons' satellite and meets their Director while the Doctor forces the Chameleon Meadows to tell him the aliens' plans.

The Doctor and Pinto are captured by the Chameleons but the Doctor manages to use their dependence on their human originals to create dissent in their ranks.