Grace McKenna, enjoying a simple life in Portobello, Scotland, is drawn into a mystery when Sylvia Gordon seeks her help in investigating her husband Paul's suspicious death. With journalist Tobias Sloan, Grace discovers hidden animosities and motives among Paul's associates. Another death intensifies the investigation, leading Grace to uncover a shocking secret linking both victims. Grace navigates personal and professional challenges to solve the mystery.

Detective Grace McKenna investigates the theft of a priceless Fabergé egg from Sacha Komorov's estate, Castle Traprain. The case takes a dangerous turn when Komorov's wife seeks Grace's help with a stalker, revealing deeper secrets within the estate. A murder within the household raises the stakes, and Grace races to solve the mystery of the egg theft and the subsequent killings, all while facing threats to her own life.

When Eliza Anderson hires the Portobello Detective Agency to find her missing sister, Grace McKenna's investigation leads her to Whiteadder House, a clinic with a too-good-to-be-true facade. As Grace and her team uncover corruption protecting the clinic, they find themselves without police support. The discovery of a body linked to the clinic escalates the situation, forcing Grace to risk everything to infiltrate Whiteadder House and save the missing sister.