 A well-to-do man swallowed potassium cyanide. A homicide is suspected. The suspects are numerous as in his lifetime the dead man dealt with fishy parties. Some of them owe him money, others are eager to rob the later. The inspector in charge of the case meets everybody, who knew the man closely. In the course of the investigations, he reveals their secrets, hidden intentions, and dangerous delusions. Gradually, the mystery is solved: the man committed suicide, as he was incurable: a sad end to a tangled life.