It is autumn 1954, and after the success of Molly McQueen's detective agency, she decides to add a new domestic branch. It is not long before one of the newly hired employees, Maisie, uncovers a riveting mystery by accident while visiting a client. Vera Barton's husband Dave and young daughter Etta went missing in 1930. After Dave's body was found, everyone assumed the worst. But decades later, Molly reluctantly agrees to take up the search for the long-lost child, and ends up unravelling a tale of misery and revenge, laced with family secrets and heartbreak.