Myrtle Hardcastle has no desire to go on a relaxing travel excursion with her aunt Helena when there are More Important things to be done at home, like keeping close tabs on criminals and murder trials. Unfortunately, she has no say in the matter. So off Myrtle goes—with her governess, Miss Judson, and cat, Peony, in tow—on a fabulous private railway coach headed for the English seaside. Myrtle is thrilled to make the acquaintance of Mrs. Bloom, a professional insurance investigator aboard to protect the priceless Northern Lights tiara. But before the train reaches its destination, both the tiara and Mrs. Bloom vanish. When Myrtle arrives, she and Peony discover a dead body in the baggage car. Someone has been murdered—with Aunt Helena’s sewing shears. The trip is derailed, the local police are inept, and Scotland Yard is in no rush to arrive. What’s a smart, bored Young Lady of Quality stranded in a washed-up carnival town to do but follow the evidence to find out which of her fellow travelers is a thief and a murderer?