The Bletchley Circle

Former Bletchley Park worker Alice Merren is in prison awaiting trial for the murder of the eminent scientist John Richards; Jean attempts to regroup the circle in order to help establish the innocence of one of their own.

Following the discovery of Lizzie Lancaster's true identity, the women race against time to establish Alice's innocence and save her from hanging.

After Millie is released from her abductors, she -- along with Alice, Jean and Lucy -- makes a horrifying discovery.

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