The Bletchley Circle: San Francisco

It's 1956, two years after we last saw our women, when Jean is confronted with evidence that the killer who struck down a Bletchley girl during the war… has resurfaced in San Francisco. With a scrap of war-time code from an American counterpart (a brilliant cryptographer who worked in the Presidio) Jean and Millie set sail to San Francisco to locate some of those code-breakers, who they hope might be able to lend support to their investigations. Decoding the decade-old teletype message leads them to an underground jazz club in the heart of San Francisco, where they meet Iris — an American musician and math genius who served at the Presidio during the war. She, along with her young engineering prodigy Hailey, is convinced to join forces with their British visitors, in order to track a series of murders that have shattered the Fillmore District — a vibrant downtown neighbourhood where Iris happens to live. His twisted signature: cutting out victims' tongues and drawing an inexplicable box on their palms.

Subsequent deaths make it clear: San Francisco is in the grip of a killer with a dark and complex agenda and is now menacing Iris's own neighbourhood. The four unlikely allies struggle to work together - and in the process, not only expose a twisted operation, but also forge powerful and lasting bonds.

The four women delve into the mysterious death of Iris's suburban friend, uncovering a complex cluster of marriages built on lies and deception. In her quest to forge a new life, Millie must confront a long-lost cousin, who may hold the key to her future in San Francisco.

After a seemingly innocent man is charged with murder, the women become enmeshed in a tangled suburban tragedy, racing to find both the true killer and the methods before the scent goes cold. Meanwhile, Jean grapples with how — and where — to build a new life for herself.

A bloodied and battered stranger collapses on Millie and Jean's doorstep, dragging them into a mysterious criminal underworld.

Having uncovered a covert system of police corruption, the women must go it alone, crafting a complex sting operation in order to draw out two warring factions and see justice done.

When a Russian diplomat dies in Iris's arms, the FBI sweep in to control the story and rule the death accidental and Iris is forced to get involved to protect her family.

A death in the Big Bop Club brings an international incident right to their doorstep, while the women grapple with Jean's sudden disappearance.