A battered man's corpse lies in the paddock of a breeding bull. Dr. Graf notes that the stranger died of a broken neck and was apparently deposited with the cop to cover up the murder. The dead man is identified as the stable boy Josef Swoboda. At the same time, Brandtner receives the news that the expensive jumping horse Sirius has been kidnapped from Hermine Latzki's riding stable. What is the role of the shady trainer Arthur Stein, who seems too eager to link Svoboda to the disappearance of the horse? When Rex Stein catches him training a horse using cruelty to animals, Brandtner begins to suspect that Sirius has fallen victim to an accident and that Stein could be the mastermind behind a sophisticated insurance fraud...