In 1975, the British Government quietly closed down a secret evolutionary project codenamed BEAGLE, ordering the destruction of all research materials. Today, the horrific discovery of several oddly mutated bodies alerts Liz Shaw and P.R.O.B.E. to the fact that something is stalking the original site of project BEAGLE – something which may challenge the very nature of humanity itself! With a crack security team at her disposal, Liz desperately attempts to track down the perverted results of the project. But who or what is hunting whom?

Two years have passed since the Nestene creature vanished from UNIT's top secret Warehouse... Suddenly and without warning the Nestene strikes, once again using Autons as its deadly foot soldiers. As mysterious UNIT operative Lockwood struggles to unearth the Nestene plan, he finds himself drawn to remote Sentinel Island. There, the population have been caught up in a bizarre frenzy of religious activity. Lockwood is joined by Natasha Alexander, a new scientific advisor with her own, sinister agenda. To defeat the Nestene menace they must both face the terrifying power of a creature from before the dawn of Mankind...

In a top-secret UNIT warehouse Dr Sally Arnold is studying a Nestene energy unit with little success. Until she subjects it to cosmic signals that activate it and it awakens several dormant Autons stored in the facility.

Retired commander of the United Nations' Intelligence Taskforce, and long-time associate of the mysterious time traveler the Doctor, Brigadier Alistair Lethbridge-Stewart faces the toughest battle of his military career when he is embroiled in a plot unwittingly set in motion by university chancellor Victoria Waterfield, herself a former companion of the Doctor, to take over the Earth by an evil alien entity called the Great Intelligence, aided by its ferocious robot Yeti cohorts. Can the Brigadier defeat this menace to the Earth without the Doctor's help?