The little genius, Armand de Trouville, is dead. He's left no heirs, no will, no beneficiary, and no relatives. Prior to Trouville's move to Milwaukee in 1936, his life is a blank. His business associates ask the Milwaukee police for help in finding any heirs, and Detective Lieutenant Joe Sonntag takes on the task as a courtesy. There's nothing unusual about Trouville's death at 68 of heart failure. The man was a diabetic. But something about the death stirs suspicion in Sonntag's chief, Captain Ackerman, who insists that something's wrong. Sonntag struggles with the enigma and with Ackerman's crazy demands until he's ready to quit the department and sell vacuum cleaners for a living. But gradually he learns more and more about what happened one cold night in a Milwaukee office building, and uncovers a crime that leads him to a killer hidden in plain sight.
