Deep space, an unknown time. The TARDIS encounters a disabled Skonnon battlecruiser transporting Anethan 'tribute'. The co-pilot is determined to reach Skonnos at any cost.

Having reached Skonnos, Romana is sent with the Anethians to face the deadly Nimon.

The Doctor and Romana are trapped in the Nimon's lair. Is he really the last of his race? What are his real intentions toward Skonnos?

Romana is trapped on a ruined planet. The Nimons are launching their invasion of Skonnos. Can the Doctor stop the 'Great Journey of Life' ?