A woman is strangled in the bath by a black-gloved killer who disposes of her body in a large trunk. The trunk is delivered to St. Hilda College, an exclusive finishing school. Betty-Anne, one of the female students, is strangled in the school cellar. The police, led by Inspector Durand, are called in to investigate. Suspects include La Floret, the voyeuristic gardener; Di Brazzi, the new swimming instructor; Mrs. Clay, the summer school French mistress; an old professor who collects birds; and a philandering young teacher called Richard. The murders continue but Jill, a keen amateur detective, helps the police identify the unlikely killer...
as Richard Barrett
as Lucille Moffat
as Jill
as Denise
as Mrs. Clay / Peter Moffat
as La Foret
as Detective Gabon
as Miss Transfield
as Miss Martin
as Professor André
as Di Brazzi
as Policeman
as Simon
as Betty Ann
as Margaret
as Wendy
as Cynthia Fellows
as Maid
as Inspector Durand
as Blond Policeman (uncredited)