On the eve of May Day, dark elemental forces begin to disturb the village of Devil's End as the Master summons the demon Azal: unexplained murders, a stone gargoyle come to life, and a nigh-impenetrable infernal energy dome. With the Master fully prepared to destroy the Earth, the Doctor and UNIT - aided by a benevolent practitioner of witchcraft - battle the wicked rites of a secret science wielded by an alien from another world.
Jon Pertwee
as The Doctor
Katy Manning
as Jo Grant
Nicholas Courtney
as Brigadier Lethbridge-Stewart
Richard Franklin
as Captain Mike Yates
John Levene
as Sergeant Benton
Roger Delgado
as The Master
Stephen Thorne
as Azal
Stanley Mason
as Bok
Damaris Hayman
as Miss Hawthorne
Don McKillop
as Bert the Landlord
Rollo Gamble
as Winstanley
Robin Wentworth
as Prof. Horner
