Arriving on Tara, Romana locates the fourth segment of the Key to Time with ease. But getting it away proves more difficult, as she is captured by the scheming Count Grendel who wants the throne of Tara for himself.

The Doctor must employ a desperate gambit to keep the evil Grendel off the throne. And the Count has a new pawn to play - Romana.

The battle for control of Tara turns into a duel of wits between the Doctor and Grendel. But the Count shows he has more treacherous tricks up his sleeve.

Grendel plans two weddings and a funeral to cement his hold over Tara. The Doctor and K-9 race to foil him and save the Time Lady's life.

Searching for the sixth segment, the Doctor and Romana land in the midst of a brutal nuclear war between the planets Atrios and Zeos.

Swept up in an apocalyptic war, the Doctor must help the Marshal defend his planet. But who or what controls the Marshal?

The Doctor meets a new enemy – the Shadow – who wants the Key to Time. And the Atrian-Zeon war is approaching an awful climax.

The Doctor is forced into a desperate gambit to prevent a massacre. But it is getting harder to tell friend from foe.

The Doctor and Romana finally venture into the Shadow's lair. The Shadow appears to hold all the cards but the Doctor has found an old friend.

The Doctor and the Shadow have their final confrontation to take control of the Key to Time. Completing it may entail an awful sacrifice. And the Black Guardian will do anything to obtain it and plunge the Universe into chaos.

Paris, 1979. The Doctor and Romana are here on holiday, but something is disturbing the flow of time. Could the time travel experiments of Count Scarlioni be to blame?

Captured by the Count, the Doctor and Romana uncover an elaborate plan to steal the Mona Lisa. But there is more to Scarlioni's plans than a simple theft.

The Doctor and Romana unwrap an intricate plot involving aliens, time travel and the Mona Lisa. How is Count Scarlioni living in two times at once? And what does he want?

Scaroth is determined to go back 400 million years in time to prevent a mistake. But the Doctor must stop him – because the consequences would be disastrous.