A widowed English writer brings his young, glamorous new bride (Britt Ekland) to his bleak, isolated home in rural Spain.
She soon becomes obsessed with her 12-year old stepson (Mark Lester) who she learns has just been expelled from school for mysterious offences.
He is obviously a brilliant and lonely child, but he also enjoys, exploits, and feeds her increasing paranoia about him.
It’s clear from the outset that the boy finds her attractive and she begins to suspect that he may have murdered his mother, who mysteriously died in a bathtub accident.
This English/Italian co-production was originally titled Diabólica Malicia and released in some markets as Night Hair Child.