Lucy and Claire are at a house where Lucy used to work. The two of them hack into the safe behind a picture. Inside are several jewels. Claire warns Lucy to leave, but Lucy says that the home-owners are on vacation and the butler is the only one at home; however, he is at the back of house. She says that they have all the time in the world. However, a few seconds later the butler walks in on them. He sees Lucy and recognizes her, but does not see Claire; Claire whacks him on the head with something, knocking him out.
Lucy tells Claire to take the jewels and give her half when she gets out of prison, where she will undoubtedly go. She heads to a local club where she sees her ex-boyfriend Tom eyeing his new girlfriend Ann. Jealous and angry, she takes a necklace she kept in her jacket pocket, which she stole from the house, and puts it in Anne's jacket pocket, without anyone seeing.
The police come to Ann’s house and ask her if she knows of any stolen jewellery, for Lucy has told the police that she was her accomplice. Ann denies this, but the police find the necklace in her coat pocket. She is sentenced to three years in Wilsham, a prison with no bars on the windows and they rely on your honour not to just walk out. They also do not like to call it a prison.
Everybody comes to hate the wardress of the girls, Miss Smith. Ann, as she was a secretary before coming to Wilsham, is told to help the Matron with her secretarial business, which Ann accepts willingly. Meanwhile, Lucy starts to pit all the girls against Ann, except for one, Mary, who has served four years in Wilsham and is getting out in one week.
The girls decide to have a party for Mary and when the wardress is gone, they have pie and celebrate. However the wardress hears the noise just before she leaves and goes to investigate. Oblivious with her eyes closed, Mary continues dancing around while the wardress is still in the room. The wardress tells her that she may have another 12 months in prison for this and then takes her away. In the morning when they go to work the girls find that Mary has hanged herself.
When questioned about if anything she could have said indirectly have caused Mary to hang herself, Miss Smith denies this.
The girls then start a riot led by Lucy and Jane. They hurt Miss Smith's arm and trash the kitchen. The only one that doesn't participate in the riot is Ann. All the girls are sentenced to a punishment except Ann. She asks the Matron if she can have the same punishment as the rest of the girls, and the Matron hesitantly complies.
Jane then talks to Ann and apologises for her actions towards her and tells Ann that she knows she’s innocent of the crime she was accused of committing. Jane tells Ann to talk to dear old Moran and leaves it at that.
Ann than climbs out the window after stealing the Matron’s coat, tells Tom to talk to dear old Moran and then turns herself in to the police. Her sentence is extended. Tom finds Moran, the owner of a pawn shop, who reveals that Claire pawned all the jewels and told him a false story. He checks the police record for stolen jewellery and finds all the pieces there. He calls the police who find Claire and bring her into the station. They also bring Lucy into the station who denies that Claire is her partner; however, when she finds out that Claire pawned all the jewels, she becomes outraged and has a fight with her, and then tells the police that Claire really was her accomplice.
Ann is released from prison.
Ann’s innocence is ultimately revealed after Tom finds evidence from Moran, the pawn shop owner, clearing her of the crime for which she was wrongfully convicted.
The ending underscores the film’s central concern with justice and institutional failure. Ann’s ordeal in the reform school, compounded by betrayal and indifference, is only resolved when external evidence comes to light. Her exoneration serves as both a critique of systems that too easily condemn the innocent and a testament to perseverance in the face of overwhelming odds. The film closes with a sense of hard-won vindication but leaves the scars of Ann’s experience lingering, highlighting the cost of wrongful accusation.