After the death in strange circumstances of Mr. Montevidei, his stepson seems the main suspect, since his car has been seen near his stepfather's house the night he died. When he is arrested and taken to the police station, he jumps out of the car and undertakes the escape, so the suspicions increase. In addition, Doria, an inspector of the insurance company who ends up creating false evidence to implicate him, is involved in the investigation.