Petersburg. Week before Christmas on 1914. Law student Peter Chukhontsev practices as a private detective. Eccentric inventor Kuklin died. Moreover, he died in the circumstances that were predicted and simulated as a suicide. It is strange that the police willingly supports this version: normal suicide of abnormal, the case is closed and the body is buried. But Petya’s deductive mind immediately tells him that is a central figure in the crime is "German-pepper-sausage" Stolz who is "The owner of mechanical curiosities exhibition " and adviser of German Embassy Siegfried Gay. And this is are very high and dangerous horizons for student’s dropouts ...