An investigation of a murder leads not only to aliens hunting humans for sport, but to a wider conspiracy by the human government that allows it to happen.
The Doctor arrives to find scavengers, a deserted London and UNIT requesting his presence in the drought-ridden city. It is all part of a plot by the Cybermen to hold the world for ransom and the Doctor and UNIT have very little time to save the planet.
The Sixth Doctor and his companion, Peri encounter a travel agency that uses alien technology to transport people’s consciousness to points in time to relive various adventures.