Another adventure for everyone's favourite Time Lord. The Doctor (Tom Baker), Sarah and Harry land on space station Nerva, where the chosen few of the human race are in suspended animation, awaiting the call to revive. However, an insectoid alien life form known as the Wirrn has infiltrated the Ark and cut through the humans' alarm clock. The Wirrn now intend to use the sleepers as the hosts for their hatchings and claim the Earth as their own.

The Doctor (Tom Baker) and Sarah Jane return for a visit to Earth, only to discover that a wave of evil Mandragora energy has hitched a ride on the TARDIS and is now being used to plunge mankind back into the dark age. They have to thwart not only the murderous count, but also prevent the mad monk Heironymous and the Cult of Demnos from unleashing the Mandragora Helix on mankind.

The entire second season of the 1970s BBC sci-fi series. 'Redemption' sees Orac's prediction of the Liberator's destruction looking likely to be fulfilled when the ship's original owners arrive and take the rebels prisoner. In 'Shadow', Blake becomes involved with an interplanetary crime syndicate. 'Weapon' sees Blake and crew set out to steal a deadly 'delayed-effect' gun, which Servalan also wishes to possess. In 'Horizon', the Liberator heads for the edge of the Galaxy, only to be taken prisoner on the planet Horizon. 'Pressure Point' sees Blake attempting to destroy the Federation's control centre, only to walk into a trap set by Travis. In 'Trial', Travis is made a scapegoat by Servalan for their failure to capture Blake. 'Killer' sees Blake and his crew stumbling upon a derelict spaceship whilst on a mission to crack the Federation's new transmission code. The craft houses a deadly plague which could threaten the existence of the entire universe. In 'Hostage', Travis tries to trap Blake by kidnapping his cousin, Inga. 'Countdown' sees Blake and crew coming to the aid of the planet Albian, whose population are dying from radiation poisoning. In 'Voice from the Past', a telepathic signal forces Blake to reroute the Liberator to an asteroid where Travis lies in wait. Whilst 'Gambit' sees Blake, Cally and Jenna visit a gambling world to find the man who knows the location of the Federation's Star One. Avon and Villa, meanwhile, choose to take Orac on an illicit gambling spree. In 'The Keeper', Blake tries to obtain the key to Star One from a tribal chief on the planet Goth. However, Travis has beaten him to it. Finally, 'Star One' sees Blake at last launch his attack on the Federation's headquarters, unaware that an alien fleet is poised to invade.

Sylvester McCoy makes his first appearance as the venerable Doctor, coming up against his old enemy, renegade Time Lord Rani (Kate O'Mara). She forces the Tardis to crash land on Lakertya, and then masquerades as his assistant Melanie (Bonnie Langford), tricking the newly regenerated Doctor into constructing a giant time manipulator designed to drain the minds of history's greatest scientists.