Part Four
Series Episode Number: 606World Premiere: Fri 13 Jan 1984 - 6:40pm GMT [BBC One] (United Kingdom)
First Broadcast: Mon 11 May 2015 - 8:30pm EDT [Retro TV]
Running Time: 24 minutes 48 seconds
6.60 Million (UK)
Appreciation Index: 65 (UK)Chart Position: 87 () (UK)
Lethal hexachromite gas is used against the reptilian threat. World war is avoided but many lives are lost and the Doctor reflects there should have been another way.