Kelville-by-the-Sea, an outwardly quiet seaside town on the northeast coast of Scotland, is the setting for this sequel to It Began with the Marbles. The story begins with the sudden death of an elderly man who served during World War Two as a guard at the town's famous glass factory. Local police officer Helen Griffen treats the death as an accident, but questions are raised that lead her to wonder if the man was murdered. Her suspicions may be too late, as any physical evidence has been compromised.

Aided by a visiting American private investigator, Alistair Wright, and his lawyer fiancée Margaret Milford, Helen starts to quietly investigate the man's background. She soon learns that a number of people might have wanted him injured or dead. Meanwhile, her son, also a private investigator, is furious that Helen is handling the case herself: she has a personal relationship with the dead man's son, and the dead man's grandson is her sergeant.

Although Margaret is supportive of Alistair's efforts to help Helen get to the truth, she can't help resenting how much time he's spending, with no chance of compensation for his professional expertise. And when Margaret gets pulled into a meeting with the dead man's lawyers, she worries that her inexperience will send the investigation along the wrong path. On a personal level, she is impatient to resolve things with Alistair: will they return to Maine soon and marry there, or stay on in Scotland? The indecision is weighing on both of them.

Gradually, Helen learns that the outwardly peaceful town harbors deep secrets from the war years, and that the dead man might have been implicated in the death or disappearance of evacuee teenagers who were sent to Kilvellie as war broke out, to escape the risk of bombing in the cities. Powerful forces in the town are trying to keep the truth from Helen. Yet, when she finally learns what she now believes to be the sad truth, an elderly resident of the care home where the dead man lived comes forward with an entirely new interpretation of the tragic events during Kilvellie's war years.