Triple-bill of Hong Kong 'Category III' erotic action thrillers. In 'Evil Instinct' (1996), cop Sam Hui (Bowie Lam) falls for Penny (Carrie Ng) after she picks him up in a bar. However, when he has to investigate a series of murders at the insurance company where Penny works, Sam discovers that Penny is selling sex for favours after losing her clients to Wendy (Diana Pang Dan), and becoming desperate due to her addiction to a snake serum drug. Sam is forced to connect Penny to the killings when it transpires that all the victims had snake DNA in their blood. In 'Naked Killer 2' (1993), a serial rapist (Mark Cheng) is responsible for terrorising the women in his apartment block and selects his attractive neighbour (Jacqueline Ng) as his next victim. Aware of his plans though, she asks her friend (Chingamy Yau) to seduce the rapist and exact a bloody vengeance on him. Finally, 'Her Name is Cat' (1999) follows the mysterious Cat (Almen Wong Pui-Ha), a professional assassin who gradually begins to fall in love with the policeman investigating her crimes.