Mr. Hex was the first Bowery Boys epic in which the goofy Sach (Huntz Hall) is given superhuman powers. Hypnotized by a carnival magician (Ian Keith), Sach becomes a powerful boxer. Head Bowery boy Slip (Leo Gorcey) parlays this talent into a lucrative ring career for Sach, culminating in the championship bout. A gangster (Ben Welden) learns Sach's secret and hires his own hypnotist to put the "whammy" on the would-be champ. The fantastic elements of the story come crashing to earth when Sach's pal Gabe (Gabriel Dell) is shot by the gangster, but all ends sappily ever after. Mr. Hex was the fourth in Monogram's "Bowery Boys" series.