Just out of jail and vowing to go straight, former jewel thief Boston Blackie, undertakes the reformation of a pretty blonde who has stolen a necklace from a cabaret dancer. He learns that the jewel belongs to the mother of the blonde girl, and the blonde's philandering father gave it as a gift to the cabaret girl. Now, Blackie must find a way to return the necklace to the owner's safe without arousing the suspicions of the girl's family.

Alcoholic playboy Wallace MacDonald (as Bruce Armstrong) would like to sober up and become more responsible, after a drinking accident causes him to cripple little brother Pat Moore (as Jimmy Armstrong). Still, the lure of liquor makes him to sneak drinks at home, and go out partying with carefree showgirl Clara Bow (as Marilyn Merrill). He's promised Ms. Bow he'll quit drinking and gambling. Further complicating Mr. MacDonald's life are the bad checks he's been accumulating. Nasty Stuart Holmes (as Tom Canfield) and Tom Santschi (as "Big Joe" Snead) force MacDonald to join their diamond smuggling racket, in lieu of payment.