Upon arriving at the building where he works, Pedro finds the janitor, Hilário Garcia, dead inside one of the elevators. Inspector Canovas, in charge of the case, discovered that Hilário was Portuguese, widowed, with an only child living in the United States. Several suspicious people are detained and interrogated and, during the investigation, a guard and a girl are killed. With the help of the North American police, Inspector Canovas discovers that Hilário's son, Antônio and his wife Vanda, had already returned to Brazil. The two are located in São Paulo and detained for investigation. At the police, Antônio confesses to Carlos, his brother-in-law, that he was responsible for his father's death. Based on these statements, Canovas concludes that the caretaker was murdered because he discovered that his son and brother-in-law made a living from various suspicious businesses and were acting outside the law.