When Dr Lauren Anderson agrees to Thomas Mordley testing his experimental new drug Cyberon on her brain damaged patients she expects little benefit. But Cyberon is going to revolutionize medicine and maybe even the world.

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 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?

A reluctant Solomon (Colin Baker), along with his former associates Egan (David Troughton) and Saul (John Wadmore), have (they think!) escaped Earth and returned to their own dimension. But a mysterious force returns them to Earth and drops them right into the middle of a top-secret experiment involving a young girl's mind powers. They soon find that the experiment has gone wrong and unleashed something deadly...and unless they can find a way to stop it, they and the experiment's team members will all soon be dead!

Former UNIT luminary Liz Shaw and her assistant Bayliss are investigating a series of bizarre murders, all committed near a soon-to-be-closed psychiatric hospital. When the hospital is unexpectedly reprieved by rich Industrialist Peter Russell events seem to move out of Liz's control. Are the incumbent director of the clinic, Doctor Dove and his predecessor Doctor O'Kane harboring the killer? What is the centuries-old horror hidden in the grounds? And what exactly is the secret of room zero?