Sophie Rundle

Four women who worked as codebreakers at Bletchley Park have taken up civilian lives. Susan has collated data about a series of murders. She tries to convince the police she knows where another body is, but they are unable to locate it and dismiss her. She turns to her three friends and they work out where the next victim will be taken, find the body, and then decide they are the only ones who can track down the killer.

Maud is convinced something horrible happened to her best friend, Elizabeth, but in her search discovers it may be entwined with another disappearance from her childhood. The answers seem within her grasp, but the onset of dementia keeps pulling them through her fingers.