An astrologer trusts the stars to make him a championship boxer.

Dustin Willoughby, a bumbling busboy, moonlights as a boxer in order to pay for instructions in his favorite subject--astrology. After a particularly painful bout, Dustin, who believes that his success as a "Taurus" depends on the appearance of the moon, goes to see his fiancée, Diane Basscombe, and is followed by a stray dog, whom he names Zodiac. When Dustin announces to Diane and her nouveaux riches parents that he cannot marry in June because of an unfavorable alignment of the planets, Diane breaks their engagement and throws him out of her house. Later, the busboy warns Judge O'Day, who is celebrating his birthday at Dustin's restaurant, that misfortune will befall him that day. A moment later, a potted plant falls on the judge's head, astounding not only O'Day but also his guest, professional gambler James J. Regan. The superstitious Regan then asks Dustin to predict the outcome of a dog race, and Dustin, after learning the birthdays of the competing dogs, picks the winner. Convinced that Dustin will bring him good luck, Regan orders Lefty, one of his minions, to bring him the retreating busboy. Dustin, however, believes that Regan is angry with him and, to avoid capture, dresses in a chorus girl costume and runs from the restaurant. Now jobless, Dustin tricks carnival barker and magician Larry Burke into hiring him as a fortune-teller. Dustin soon becomes the carnival's star attraction and wins the heart of Larry's secretary, Jerry Grant. Jealous of Dustin's success, the smooth-talking Larry informs the police that Dustin has no operator's license, and Dustin is arrested. By coincidence, Dustin's case is heard by Judge O'Day, who recognizes the former busboy and informs Regan of his whereabouts. Regan installs Dustin in his offices and consults him religiously on his various wagers. One night, while appearing as the "Great Swami" in a stylish dinner club, Dustin is spotted by Diane and her parents. Impressed by Dustin's successes, Diane showers him with affection and kisses him in front of Jerry, who runs from the club in humiliation. Unable to contact Jerry, Dustin grows despondent and leaves town to find her. While he is away, Regan and Lefty, who are worried about an upcoming boxing match in which they have entered foreign slugger "Salvador Slayer," mistake Dustin's positive astrological chart for their boxer's. When Dustin returns without Jerry, he informs Regan that the boxer's planet alignments are unfavorable. To Dustin's dismay, Regan then insists that he take the boxer's place in the bout, which begins shortly before moonrise. After a near defeat in the first rounds, Dustin, inspired by the appearance of the moon, routs his superior opponent and is embraced by a forgiving Jerry.