From a state-of-the-art bunker beneath the Tower of London, Kate Stewart leads a secret army protecting the Earth from extraterrestrial threat. Crashed UFOs, strange meteors, a giant lizard in the Severn - all business as usual for UNIT.
Lieutenant Sam Bishop is finishing an assignment in Bangkok when he receives a call from Kate Stewart. She has a new job for him - hunt for a stray Nestene energy unit that has come down somewhere in the Gobi desert.
As Autons swarm across the planet, the human race faces its darkest hour. Simon Devlin has helped his alien masters gain a global foothold and their scheme is almost complete.