Jean Raymond an upper class woman with a gambling addiction, is given a twelve-month prison sentence resulting from her inability to pay her debts. At first she is overwhelmingly depressed by life in the women's prison; gradually, however, her misery is relieved by the many close friends she makes there. This sympathetic drama traces the contrasting lives and often faltering progress of the inmates of a women's prison.

When Professor Willingdon becomes wary of the nuclear weapons he is helping build, he steals a warhead and threatens to detonate it in London in seven days unless the government begins nuclear disarmament. As Willingdon goes into hiding, Detective Folland of Scotland Yard sets out to find him. Willingdon's daughter Ann also joins the cause, hoping she can talk sense into her father before he causes a catastrophe.