Sir James Forbes arrives in a remote Cornish village to identify a mysterious plague afflicting the population. Local squire Charles, a disciple of Haitian witchcraft, is using the voodoo magic to resurrect the dead to work in his decrepit and unsafe tin mines that are shunned by the local population. But his magic relies on human sacrifice and he unleashes his army of the undead on the unsuspecting village with horrific consequences.
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.
