June 1933. Independent, young Kitty Underhay has been left in charge of her family’s hotel, The Dolphin, on the tranquil English coast. But when several rooms are broken into and searched, including Kitty’s own, she quickly realizes that something out of the ordinary is afoot at the hotel. Soon, rumors are flying in the cozy town that someone is on the hunt for a stolen ruby. A ruby that Kitty’s mother may well have possessed when she herself went missing during the Great War.

Olivia Denis is a content young wife with a carefree life in late 1930s London. Then her world is shattered with the violent death of her husband, Reggie. The police want to call it a suicide and close the case, but Olivia knows Reggie couldn't possibly have fired the fatal shot. Further mysteries surface surrounding her husband's death. Did the trustworthy Foreign Office employee betray government secrets? Was his murder linked to the death of a German embassy clerk the same night? And who searched their flat?

If one more person gives Rosemary Lillywhite unwanted advice on when to stop mourning the loss of her beloved husband, she fears she will lose control of her sensibilities. All she wants is to be left alone to drown her misery in a glass of gin and tonic, but when Grace Barton knocks on the door of her dead husband’s investigative office, Rosemary faces a choice: come out of hiding, or turn away someone in need of help.

Following the death of her husband, Lady Darby has taken refuge at her sister's estate, finding solace in her passion for painting. But when one of the house guests is murdered, her brother-in-law asks her to aid the insufferable Sebastian Gage - a fellow guest with some experience as an inquiry agent. While Gage is clearly more competent than she first assumed, Kiera isn't about to let her guard down, as accusations and rumors swirl.

May 1941. One of the senior choristers of St Paul's Cathedral choir, Dr Edwin Roberts, is found beaten to death in the crypt of the Cathedral. Coburg and Lampson are called in to investigate, and when they get there, Coburg is pleasantly surprised to be greeted there by Arthur Waterson, now sporting a dog collar, someone he was at Eton with many years before. Waterson believes that there may be a connection between the very precious books that are houses in the Crypt and Dr Roberts' work at Bletchley Park.