THE TARDIS LANDS IN THE HIMALAYAS IN THE summer of 1289. A circuit fault leaves the ship without lighting, heating or water. The Doctor, his granddaughter Susan, Ian Chesterton and Barbara Wright are rescued from the freezing conditions by the famous Venetian explorer Marco Polo, who is intrigued by the Doctor’s ‘flying caravan’. He decides to offer the TARDIS to Kublai Khan, ruler of Mongol Asia, as a gift in order to win his leave after 18 years in the Khan’s employ.
Polo’s caravan includes Ping-Cho from Samarkand, a girl to be delivered to an arranged marriage in Peking, and Tegana, an emissary warlord of Noghai who intends to discuss terms of a post-war armistice with the Khan.