Hard Boiled Mahoney (1947)

The Bowery Boys (Slip, Sach, Bobby, Gabe, Whitey, and Chuck) accidentally enter the detective business with the disappearance of a beautiful girl, Eleanor Williams, as their first case to solve. They are retained by Selena, who says she is the missing girl's sister. The disappearance is doubly puzzling because Eleanor has just learned her long-lost husband, Tom Williams, is returning from South America. Slip and company trace Eleanor to the apartment of Dr. Rolfe Carter, to whom she first went when Tom was reported missing three years earlier. Slip witnesses the doctor's murder but does not know who fired the fatal shot. Slip and his friends learn Dr. Carter was a pseudo-psychic who was into blackmailing his clients and was linked up with syndicate-chief Armand. The latter and his henchman, knowing Slip has information regarding Carter's murder, set out to kill the boys.