The Bletchley Circle

Alice Merren is in prison awaiting trial for the murder of the eminent scientist John Richards. Driven by her belief in Alice's innocence, Jean attempts to reunite the circle.

Following the discovery of Lizzie Lancaster's true identity, the women race against time to prove Alice's innocence. 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 involvement in the import/export business. Worried about her friend, Alice contacts the other women to help find her.

Millie, now aware of the dark crime operation in which she had become embroiled, leads the circle to the heart of Marta's operation.