A young woman is hired to care of a wealthy but elderly man, his paralyzed daughter and his lonely but sensuous adopted daughter who all live on an island off the Greek coast.

When she arrives at the island the elderly man warns her that his daughters are evil and dangerous. The woman soon discovers that one of the daughters is a sex-crazed nymphomaniac who pursues, and seduces, everyone in the house, for her own perverted pleasures including her helpless and crippled sister!

What ensues is a cat and mouse game of treachery and lust as only director Jess Franco can deliver!