A spirit photograph. A detective in a box. A Scandinavian boy who speaks only Maori and runs with the Marsh Mob. A body floating in the marsh. And a new opportunity for James Hardy to exercise his mind.

New Zealand 1882: When Constable Patrick Foster pursues a young, blond boy who runs with a gang of Maori boys, he discovers he speaks only Maori, even though he is clearly Scandinavian. After the boy jumps from a bridge into a fast-moving tide, Mr. Hardy and Constable Foster search for his body in the the marsh. But they find a different body than they expected. While Inspector Scully investigates the discovery, James Hardy looks for the boy's family in the Scandinavian settlements. His investigation uncovers a family tragedy, but will it also lead to the body in the swamp?