Although the men in her family have a long history of disastrous gambling addictions, Mary Audrey is determined to keep her grandfather, William Audrey, away from temptation and forces him to work in her Beverly Hills book store. As soon as "Gramps" is left alone in the store, however, he is approached by Larry Scott, a well-heeled gambler, who innocently asks him for a racing "scratch sheet." Believing him to be a bookmaker, Larry places a $200 bet with the obliging Gramps. When Larry's horse wins, Gramps takes off, as he is unable to cover the wager, but is quickly waylaid by Larry, who has since met the pretty Mary. Mary and Larry soon fall in love, and Larry, who has not told Mary of his vocation, vows to Eddie, Sacramento Sam and his other cynical gambling mates, that he is giving up the betting life. Before Larry can come clean with Mary, however, he is caught in a police raid and exposed in the newspapers. Disgusted, Mary at first refuses even to talk to Larry, but after he convinces her of his sincere convictions, she accepts his proposal. Following a quick Las Vegas wedding, Mary and Larry check into a local hotel for their honeymoon. A trusting Mary then leaves Larry alone in the hotel, and Larry soon finds himself in the gambling room helping a "poor sucker" recoup some of his losses. Mary returns to the hotel in time to see Larry tossing dice at the crap table and accepts an offer from lawyer Dan Morgan to file for divorce. By the end of the evening, Larry, who has been unable to explain the situation to Mary, is served with divorce papers. The next day, Sam, anxious to aid his heartbroken friend, schemes to reunite the couple by hooking Mary on gambling. To that end, he arranges with the casino to ensure her at least $500 worth of winnings, which he and Larry's gambling friends are to cover. He also hires Morgan to romance Mary and seduce her into gambling with him. Desiring Mary for himself, Morgan tells Mary that Larry is in on the plan, and when Larry, hearing of Mary's extravagent wagering at the roulette wheel, tries to stop her, she scorns him. Much to everyone's surprise, Mary's fixed winning steak turns into a genuine run of luck, and while Sam and company go broke covering for her, Mary becomes addicted to her success. The disconsolate and jealous Larry, meanwhile, returns to Beverly Hills, where he finds Gramps running a bookie joint out of Mary's store. After Gramps shows Larry the Audrey family "album," Larry realizes that Mary is a victim of heredity and rushes back to Las Vegas to save her. When he arrives, he discovers that she has bought her own casino and has installed Gramps as the house poker player. Once again, Sam offers to help Larry reclaim Mary by playing Gramps in a high-stakes poker match using Larry's money. Although Gramps holds the winning hand, he sacrifices the game so that Larry can finally win back Mary, who has learned of Larry's intentions from Sam. While Sam and his partners become the owners of the club, Larry and Mary leave for a real honeymoon, and Gramps happily loses his last pennies at the roulette wheel.