Part OneSeries Episode Number: 392
World Premiere: Sat 8 Mar 1975 - 5:30pm GMT [BBC One] (United Kingdom)
First Broadcast: Tue 11 Mar 1980 - 5:30pm CST [WTTW 11 Chicago]
Running Time: 24 minutes 20 seconds
10.70 Million (UK)
Chart Position: 23 () (UK)
Recorded on Mon 27 Jan 1975 in TC1
The Time Lords send the Doctor, Sarah and Harry to Skaro at a point in time shortly before the creation of the Daleks. The Doctor's mission is to destroy his greatest enemy.