The travellers arrive in the dangerous domain of the Toymaker, where their failure to win at a series of games could result in them becoming his playthings for eternity. Apparently innocuous nursery characters reveal deadly intent, and for companions Steven and Dodo the stakes are raised with every game of blind man's buff and musical chairs. The Doctor, meanwhile, is rendered invisible and given the challenge of completing the fiendishly difficult Trilogic game.

The TARDIS lands on the seveneenth century Cornish coast, and its crew stumble upon a plot by the local Squire to receive and offload contraband goods. The Doctor meets the churchwarden, whose last words to him concern the whereabouts of hidden treasure. When pirate captain Samuel Pike learns of this, he kidnaps the Doctor and demands to be given the cryptic clue.

The TARDIS materialises at the Roof of the World, Central Asia, in 1289. There they meet Marco Polo and his fellow travellers on their mammoth journey across the Pamir Plateau and through the Gobi desert to Peking. Unfortunately for the Doctor, his Ship proves to be of immense interest to Polo, who sets his mind on presenting it to the mighty Kublai Khan on arrival at his court.

When the TARDIS materialises on an alien planet, the Doctor insists that he and his companions have arrived in the far future. Steven and Dodo think otherwise, however, after they encounter a band of cave-dwelling primitives who are terrified of strangers.

The Doctor has adopted many guises in his time, but to be hailed as the great god Zeus is a bit of a shock. Yet this is exactly what happens when the TARDIS lands on the plains of Asia Minor, not far from the city of Troy. Taken to the Greek camp by Achilles, the Doctor is introduced to Agamemnon and Odysseus and forced to admit his less¿than¿godlike status. He is then given just two days to come up with a strategy for defeating the Trojans.