The Doctor lands the Tardis in 1215 England at the Castle of Ranulf Fitzwilliam in the middle of a jousting tournament and the Doctor is immediately hailed as a demon by the king. The Doctor finds this very suspicious. SPOILER ALERT: If you are watching this episode for the first time, wait until it is over to view the main cast as that will give some of the plot away.

The Doctor finds his past selves being ripped away one by one. His past selves end on on his home planet, the world of Gallifrey. They discover that they are being transported to a place on Gallifrey called the Death Zone where Time Lords in a time long before Rassilon used to scoop up aliens from all over space and time to play deadly games with them. This was put to a end by the rise of Rassilon as the greatest of all the Time Lords. The 5 Doctors have to discover who is behind the plot.