《布莱切利四人组》的衍生剧，该剧有四个故事，每个故事两集。故事时间设定在1956年，原剧中的两个核心角色Millie和Jean来到美国，与两个美国密码破译专家共同调查新发生的谋杀案。
布莱切利四人组之旧金山 (季节 1)
Presidio 5.5
播出日期: 2018-07-25
运行时间: 45 min
概述: 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.
Wake 5.5
播出日期: 2018-08-01
运行时间: 45 min
概述: 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.
Charlotte's Web 5.3
播出日期: 2018-08-08
运行时间: 45 min
概述: 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.
Madhouse 5.5
播出日期: 2018-08-15
运行时间: 45 min
概述: After a seemingly innocent man is charged with murder, the women become involved 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 to build a new life for herself.
Not Cricket 5.0
播出日期: 2018-08-22
运行时间: 45 min
概述: A bloodied and battered stranger collapses on Millie and Jean's doorstep, dragging them into a mysterious criminal underworld.
Iron in War 5.5
播出日期: 2018-08-29
运行时间: 45 min
概述: 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.
Fog of War 5.0
播出日期: 2018-09-05
运行时间: 45 min
概述: 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.
In for a Pound 4.0
播出日期: 2018-09-12
运行时间: 45 min
概述: A death in the Big Bop Club brings an international incident right to their doorstep, while the women grapple with Jean's sudden disappearance.
季
集 8