MARINUS a remote force-shielded island set in a sea of acid, governed by

THE CONSCIENCE the ultimate computer which rules and balances the gentle life of Marinus, guarded by

ARBITAN THE KEEPER ruthless protector of a peace-loving race threatened by

YARTEK Warlord of the brutal sub-human Voords, sworn enemy of Arbitan and of Marinus, who has within his grasp

THE KEYS OF MARINUS the Conscience's vital micro-circuits, the doors of good and evil.

Can the Doctor find the hidden circuits in time? Arbitan's command was 'Find them, OR DIE!'

Forced off course by the Mandragora Helix, the Tardis lands in the province of San Martino in fifteenth-century Italy. Here, the court astrologer, Hieronymous, has been taken over by the Mandragora energy-form - Hieronymous and the other members of his star-worshipping black magic cult will be used as a bridgehead, enabling the Mandragora Helix to conquer the Earth and rule it through their chosen servants.

The Doctor has to defeat not only the Mandragora energy, but the evil schemes of the murderous Count Frederico who plans to usurp the place of his nephew, the rightful ruler of the province.

PLANTS ATTACK MAN

In the frozen reaches of the Antarctic, deep in the permafrost, the World Ecology Bureau uncovers two of the strangest pods ever known to man - two pods that have been buried in ice for thirty thousand years.

Then, one of the pods is destroyed, and the second is stolen...

The pod is an alien Krynoid - hostile to all animal life - including man. Only Doctor Who is able to stop its spreading tentacles of destruction. But will he be in time to save mankind?