Vendetta (1986)

Stuntwoman Laurie Collins invites her sister Bonnie to visit on location in a small town. Bonnie is accosted by a local boy whose father is influential in the community, and ends up in prison when she defends herself, victim of local political corruption. Laurie hears bad things about her sister's treatment in the hoosegow, and gets herself jailed in order to even the score with Kay the queen bee prisoner and her loyal followers.