From the liner notes

Linda (Gioia Scola) and her lover Carlo (David Brandon) committed a horrible crime: eight years ago they murdered the woman's husband, while she was pregnant with his son. They hid the corpse and since then they are running a small hotel near a popular fishing lake. One rainy night a drifter named Marco (Urbano Barberini) arrives to the hotel, but he seems to know too many details about Linda's dead husband.