Sir James Forbes arrives in a remote Cornish village to identify a mysterious plague afflicting the population. He discovers that one of the squires is a disciple of Haitian witchcraft and using dark magic to resurrect the dead. As the plan to create undead servants unravels, the squire unleashes his zombie army on the unsuspecting village.

A homely but vivacious young woman dodges the amorous attentions of her father's middle-aged employer while attempting to please her glamorously stuck-up roommate Meredith.

On the planet Vortis, the Doctor and his companions aid the butterfly-like Menoptra in their battle against the parasitic Animus and its mind-controlled minions, the ant-like Zarbi.