In one of his rare performances without Bud Abbott, Lou Costello plays a delivery boy who invents a machine which turns his girlfriend into a giantess.

Lou Wilson returns from a few years of college to live at home again only to find that his parents have adopted a 12-year-old.

Sam Bowden witnesses a rape committed by Max Cady and testifies against him. When released after 8 years in prison, Cady begins stalking Bowden and his family but is always clever enough not to violate the law.

Rose Loomis and her older, gloomier husband, George, are vacationing at a cabin in Niagara Falls, N.Y. The couple befriend Polly and Ray Cutler, who are honeymooning in the area. Polly begins to suspect that something is amiss between Rose and George, and her suspicions grow when she sees Rose in the arms of another man. While Ray initially thinks Polly is overreacting, things between George and Rose soon take a shockingly dark turn.

A gang of forty motorcyclists, the Black Rebels Motorcycle Club, gate-crash a legitimate motorcycle race. They are eventually thrown out, but one of the gang steals the second prize trophy and gives it to their leader, Johnny.

Roy puts a stop to gun smuggling.