Aggie Morton lives in a small town on the coast of England in 1902. Adventurous and imaginative but deeply shy, Aggie hasn't got much to do since the death of her beloved father... until the fateful day when she crosses paths with twelve-year-old Belgian immigrant Hector Perot and discovers a dead body on the floor of the Mermaid Dance Room! Aggie and her new friend will need every tool at their disposal to solve the case before Aggie's beloved dance instructor is charged with a crime Aggie is sure she didn't commit.