On a mission to collect the six segments of the Key to Time, the Doctor and Romana travel to the planet Ribos where the first segment is protected by the monstrous Shrivenzale. Show more

Garron is attempting to trick the Graff Vynda-K into buying the planet Ribos, but the jethrik that is vital to his plan is really the first segment of the Key to Time.

The Doctor and Romana's search for the first segment of the Key to Time is hampered when the Graff Vynda-K takes them prisoner.

Pursued into the catacombs by the Graff and attacked by the ferocious Shrivenzale, the Doctor and Romana struggle to stay alive and find the first segment of the Key to Time.

In search of the second segment of the Key to Time, the Doctor and Romana travel to the planet Calufrax. But they find that a completely different planet has taken its place. Show more

Still in search of the missing planet, Calufrax, the Doctor and Romana encounter the telepathic Mentiads and Zanak's ruler, the half man, half robot Captain.

The Doctor has discovered the sinister truth about Zanak and solved the mystery of the missing planet. On the Bridge, the Doctor meets the real ruler of Zanak.

The Doctor and Romana join forces with the Mentiads to prevent the Captain and Xanxia from using Zanak to consume Earth. Show more

The Doctor and Romana track the third segment of the Key to Time to the vicinity of an ancient stone circle on Earth. But sinister forces are at work and the stones hide a secret.

The leaders of a druidic cult have been killed and it seems that the stones from the stone circle are alive and have a taste for human blood.

As the blood-hungry Ogri close in, the Doctor launches a desperate attempt to rescue Romana from hyperspace.

The Doctor releases two alien justice machines from imprisonment but they sentence him to death! Meanwhile, Romana searches for clues that will reveal Vivien Fay's true identity.

Arriving on Tara, Romana locates the fourth segment of the Key to Time with ease, but is captured by the scheming Count Grendel who wants the throne of Tara for himself. Show more

Grendel kidnaps Prince Reynart and seems set to be chosen as Tara's monarch when Reynart fails to arrive at his coronation. But the Doctor has a plan to scupper the Count's scheme. Show more

While Romana makes her escape from the castle, the Doctor is lured to a meeting with an android duplicate of her that is programmed to kill him.

The Doctor attempts to enter to the castle to prevent the marriage of Romana to Prince Reynart and thus thwart Grendel's dastardly plans to rule Tara.

Tracing the fifth segment of the Key to Time to the third moon of Delta Magna, the Doctor and Romana are soon caught up in the conflict between humans and the Swampies.

The Doctor arrives in time to save Romana from being sacrificed to the bogus god, Kroll. But it's not long before the very real Kroll makes a terrifying appearance.

With the giant, squid-like monster Kroll awake and angry, the Swampies are eager to appease their 'god' by using the Doctor and Romana as sacrificial victims.

With Kroll on the rampage, the Doctor and Romana are appalled to discover that Thawn intends to fire a rocket at the creature which will also kill the Swampies. Show more