Totò, Vittorio and the Doctor (1957)

The fake private detective Mike Spillone is hired by two old ladies to find out if Brigitte, the wife of their nephew Otello Bellomo, has a lover. Brigitte is a physician but the two aunts are unaware of the fact. While investigating, Mike and his assistant Johnny discover Brigitte with a prospective patient, the marquis De Vitti who was shot by the husband of the woman he tried to seduce. Afterwards Spillone finds her with her husband who he believes to be her lover.