Prowling for a good time amid the debauchery of London's swinging underground scene, twins Jacki and Julian (Judy Geeson and Martin Potter) fall in with slippery bisexual gambler Clive (Alexis Kanner), who seduces and then tries to blackmail Julian. But soon the strangely intimate siblings hatch a violent plan to get revenge. This twisted exploitation tale from director Alan Gibson also stars Marion Diamond, Mike Pratt and Michael Redgrave.