An extraterrestrial alien lands in England in search of edible protein for his home planet. After attacking a young couple necking in a car, the creature assumes the body of the hapless male (Barry Stokes) and stumbles through the woods, trying to get used to his new physical form. The next morning he inadvertently trespasses on property owned by Jessica (Glory Annen), who lives in seclusion with her lesbian lover Josephine (Sally Faulkner). Jessica is friendly and invites the stranger inside when she notices him limping, though Josephine hates all men and guards their relationship jealously. He identifies himself as "Anders" (the name of the boy he killed) and quietly follows them back to the farmhouse. Both women are disturbed by Anders' bizarre behavior; he doesn't know what tea is, isn't quite sure where he came from, and vomits when he tries to eat the salad they prepare. But when Jessica begins to suspect that Josephine has taken her jealousy and hatred of males to murderous extremes in the past, she starts thinking of Anders as a possible ally. Meanwhile, Anders tests chickens, a parakeet, a fox, and a pair of policemen for their comestible value, and finally turns his appetite towards his hostesses.