Sayoko is a seasoned fraudster who specializes in the “Black Widow Business”, using her charms to seduce old men and marry them for their inheritance. She teams up with Toru, a marriage consultant who is the mastermind behind this business. Her latest target, wealthy and lonely Kozo, still has a secret fortune, which Sayoko and Toru are determined to seize！But Kozo’s daughter smells foul play, and with private detective Honda, starts the battle to save her father’s fortune.