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...
as The Doctor
as Jo Grant
as Brigadier Lethbridge-Stewart
as Sergeant Benton
as Captain Mike Yates
as Cliff Jones
as Stevens
as Elgin
as Hinks
as Dai Evans
as Dave
as Bert
as Nancy
as Milkman
as Hughes
as Fell
as BOSS (voice)
as Minister of Ecology
as Cleaner
as Yates' Guard
as Guard
as James
