The Bletchley Circle

Former Bletchley Park girl Alice Merren is in prison awaiting trial for the murder of the eminent scientist John Richards. Convinced that Alice is hiding the truth about John's death, Jean attempts to reunite the circle to help establish the innocence of one of their own.

Following the discovery of Lizzie Lancaster's true identity, the women are faced with a race against time to prove Alice's innocence and to save their friend from the hangman's noose. Then further investigations lead them to uncover a much darker military conspiracy.

Millie has been kidnapped, and it appears that it could be connected to her recent involvement in the black market. Worried but not wanting to incriminate her friend by calling the police, Alice contacts the other women to help find her. But when they go to search for Millie's business associate Jasper, it becomes clear that Millie has become embroiled in a very dangerous world.

From PBS - The women realize there's corruption in the vice squad and decide to intercept the crime ring themselves.