Millie Harcourt and Jean McBrian travel to San Francisco and join forces with two American codebreakers to pursue a serial killer from their war days.

The search for the killer terrorising the Fillmore district continues. Millie, Jean, Iris and Hailey are under pressure to work out who the killer is so they can stop them before they strike again.

As Iris struggles with husband Marcus’ imminent deployment overseas, she and the other women delve into the mysterious death of a friend - and uncover a marriage built on lies and deception.

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.