'The Doctor awakens surrounded by the Crei, aliens that look like elephants. The Doctor discovers that he is on one of their ships and that they have trapped him there thanks to a temporal trap and that has taken the city of Prague from the twenty-fourth century in the hopes of finding a device that would help them win the war. The Doctor is forced to help them in order to get the TARDIS back. He takes them through the city, stopping at different places that the device, the Tipping Device, might be. The Doctor gets a clue from the Crei that the device might be at the Old Clock Tower that is in the centre of Prague. The Crei had stopped time to help find the device and they restore it in order to get the clock working. The Doctor and Kandula, the Crei helping the Doctor, race back towards the TARDIS. The commander attacks them as they flee as he realizes that he was tricked. The Doctor and Kandula escape, but Kandula is badly wounded and dies. The Doctor actually had the device all this time as Kandula slipped it into one of his pockets. Prague is returned safely to Earth.
Years pass and the Crei ship is left in ruins floating in space. People come and dump the junk on the remains. And one lone Crei figure remains clutching a small device, thought to be the Tipping Device.'
[The Doctor is the Third Doctor.]
Source: drwhoguide.com (http://www.drwhoguide.com/whotrip23.htm). Sighted 20/5/11