In Scotland, an alien takes the body of an attractive young woman and travels the country in a van picking up men. As she lures her victims into sex, the men are trapped in a kind of preserving liquid and their organs are harvested. She is monitored by another alien, who has the body of a male motorcyclist.
When she attempts to seduce a man on a beach, she witnesses the accidental drowning of a man and woman. She watches dispassionately, then kills the man after he tries to save them. She takes his body with her, leaving the couple’s toddler behind.
When she seduces a lonely and sexually inexperienced man who has neurofibromatosis disfigurement, she takes pity on him and allows him to escape. The man is tracked and killed by the motorcyclist, who sets out in pursuit of the alien woman across Scotland.
Troubled by the encounter with the man with neurofibromatosis, the alien undergoes an identity crisis, and begins to feel more conscious of her human body; she becomes depressed and eventually catatonic. She is helped by a man who takes her to his home, cooks for her, and gives her her own bed. She trusts him and they attempt to make love, but are unable to.
Confused, the alien goes for a walk in a deep forest and takes shelter in a cabin. She is woken by a forest ranger, who tries to rape her; in the process, he tears her skin, revealing her alien body. As she extricates herself from her human skin, the ranger douses her in petrol and burns her alive. The smoke from her burnt body coils into the sky.