Parole officer Sandra Parker becomes aware of the death of one of her cases, Ginger Stratton, at the hands of brutal prison guard Claire Tyson. All too aware of Tyson's impeccable record, Parker and her friend, Assistant District AttorneyHelen Anderson, come to the conclusion that Tyson is basically untouchable. Parker hatches a scheme to expose Tyson by going undercover in prison herself. Helen attempts to persuade her that this is foolish but there is no stopping Sandra. She adopts the name Sally Porter, bleaches her hair and gives herself some needle marks as if she were a drug addict. Helen gives her boss Barney Fielder the appropriate papers for transporting "Sally Porter" to prison, where she finds herself on Ginger's "ward" and begins asking questions of her other inmates. Outside the prison, Helen Anderson is shot and killed by a boyfriend of one of her cases. Sally must therefore prove Tyson's true credentials before she can escape. Life in prison moves on and Tyson's "henchwoman" Leila becomes suspicious of all of Sally's questions. At first Tyson is angry with Sally's insolence but begins at one point to warm to her as she shows spirit. However, as Sally attempts to protect Melinda – so Sally and Melinda find themselves in an impossibly small room for a prolonged period. Just before lights out – Leila informs Sally that "the word's been passed" and Sally is due to be killed tomorrow. Sally is all too aware that she must escape and makes a run. Initially unaware of the escape attempt, the prison closes for the night – until Tyson does the usual number checks and sounds the alarm. A chase ensues with Sally still within the prison grounds, where taking one wrong turn brings her face to face with a furious Tyson. The two exchange blows before Sally pins Tyson to the floor putting Tyson's own truncheon across Tyson's throat and kneeling on it. The struggle is interrupted by the prison governor. As the pair of frantic women are separated, Sally cries out to the governor that she is in fact Sandra Parker, asking him to contact Barney Fielder to confirm her identity. As this is taking place, Tyson is frantically explaining to the prison governor that Sally had tried to kill her. Accusing her repeatedly of being "a dirty lying lousy little con". In the film's penultimate scene, the governor looks somewhat disbelievingly at Tyson as Sally cries out "Oh my God". The film ends with Sally walking triumphantly down the corridor which led to her ward – dressed in her ordinary clothes. She promises to reopen Melinda's case.
Leonard Maltin's TV Movies & Video Guide ranks the film as "verage", stating that "ood production tries hard, but script is unbelievable, performances uneven", while the write-up in Michael Weldon's Psychotronic Encyclopedia of Film opens with "he first women's prison TV-movie stars Ida Lupino as a sadistic warden." Alvin H. Marill in his Movies Made for Television also makes the same observation: "laying a sadistic prison superintendent, Ida Lupino virtually reprised a similar role fifteen years earlier in Women's Prison." Women's Prison, released in February 1955, actually preceded the January 1972 broadcast of Women in Chains by seventeen years, and both Weldon and Marill also misstated Lupino's prison position in the later film.
