Just one year after appearing onscreen together in the notorious Thriller: A Cruel Picture, Christina Lindberg and Solveig Andersson reteam for this erotic drama about a young couple caught-up in a dangerous ménage-a-trois. Paul and his girlfriend Marianne are experiencing a rough patch in their relationship when Paul invites his alcoholic father over for a visit. It isn't long before the tensions in the apartment grow thick, prompting Paul and Marianne to head out for a wild night at the movies. When they wake up the following morning, Marianne's sister Beryl is snuggled up in bed beside them. Enraged, Marianne storms out, leaving her sister and Paul alone together. But when the malevolent Mr. X lures Beryl away to a kinky stag party, Paul gives chase in a bid to rescue her from being irreparable corrupted.