Scorpion: Double Venom (1998)

A woman is searching the persons responsible for kidnapping her younger sister. Ever since her disappearance, she's kept it in the back of her mind. Her past comes back to haunt her one day when a patient is admitted into the hospital where she just happens to work. The patient brags to her that he was involved in her sister's kidnapping and tells her there's nothing she could do about it. She snaps and takes care of his loud mouth. For her crimes she's sent to a women's prison. Whilst inside she's violent abused by her fellow inmates and is constantly hit on by the bi-sexual warden. However she uncovers a shocking secret whilst in lock-up.