Inspector DeKok and his partner, Vledder, are ordered to protect a millionaire's art treasures, exhibited during a special showing in Amsterdam. Barely recovered from the shock of witnessing the treasures' owner verbally abuse an old lady, the two detectives are called away to a nearby building to help prevent the execution of a young man chained to the pipes of the central heating system. That same night, a priceless silver jug is stolen from the exhibition.

Readers face, at first, a jigsaw puzzle of more-than-usual difficulty, then slowly see a mathematically precise course of events. As with all of A. C. Baantjer's books, nothing is ever what it seems and there is never such a thing as an isolated incident. DeKok's investigations always deliver a chain reaction of events with dead ends, winding paths, and surprising endings.