The Doctor and UNIT investigate a deadly infection lurking underneath the Welsh mining town of Llanfairfach. It's an adventure that will change Jo Grant's life forever...
Jon Pertwee
The Doctor
Katy Manning
Jo Grant
Nicholas Courtney
Brigadier Lethbridge-Stewart
John Levene
Sergeant Benton
Richard Franklin
Captain Mike Yates
Stewart Bevan
Cliff Jones
Jerome Willis
Stevens
Tony Adams
Elgin
