The Faceless Ones, Episode Five

The TARDIS materialises on a runway at Gatwick Airport, and when the Doctor and his friends scatter to avoid policemen, Polly witnesses a murder in an airplane hangar. She tells the Doctor, but is then kidnapped - and reappears shortly afterwards, bearing a passport from Zurich and claiming to have no idea who the Doctor is. Jamie meets a young woman named Samantha who's looking for her missing brother, and when a detective from Scotland Yard shows up looking for his missing colleague, the airport Commandant is forced to concede that something very odd is going on. The Doctor soon discovers that "Chameleon Tours", ostensibly offering cheap package tours for students and hitch-hiking youths, is in fact a front for a massive kidnapping operation. The alien Chameleons, who lost their personal identities in a cosmic accident, intend to steal the identities of the thousands of kidnapped youths, and the Doctor and his friends must stop them. When the situation is resolved, Ben and Polly discover that this is the very day on which they began travelling with the First Doctor, and choose to remain in London.