While gem dealer Horace K. Arlington frets over the safety of his newly purchased diamond collection, which is being shipped from Europe, Dave Hanlon ingratiates himself with Horace's daughter Arlene and plots with his three cohorts to steal the jewels. As part of the scheme, Dave hires Jerry Lane and Pierre Potkins, whose carnival act includes an airplane amusement ride, to pick up the stolen gems in a seaplane. Although Pierre is scheduled to meet with his parole officer that afternoon, he and Jerry accept the job and, unaware that their seaplane belongs to the police department, retrieve from the ocean what they believe to be harmless photographs. When Pierre inspects the package, however, he discovers the jewels, as well as a box of cocaine. After becoming intoxicated from the powder, Jerry, whose only knowledge of flying has come from reading books, crash lands the plane in the Arlingtons' backyard. Horace, seeing the police insignia on the plane, assumes the two men are detectives and immediately reveals his concern over his diamonds. Frightened, Jerry and Pierre take advantage of Horace's confusion and introduce themselves as detectives to Arlene and Juanita, the Arlingtons' pretty Latin maid. Soon after, however, Dave telephones Arlene and learns about Jerry and Pierre's sudden arrival. Anxious to claim the gems, Dave tells Arlene that Jerry and Pierre are escaped lunatics. Although she is attracted to Jerry, who entertains her with Charlie Chaplin imitations, Arlene orders Juanita, who likes Pierre, to contact the police. Before the authorities arrive, however, Dave and his henchmen show up and pressure Jerry and Pierre to divulge the diamonds' whereabouts. Just as Jerry reveals where he hid the gems, Squeezy, Juanita's Boston terrier, who has been sneaking objects from the Arlingtons' house and burying them in the yard, steals the hidden jewels. Horace's gullible wife Martha then sees Squeezy reflected in her crystal ball, but is unable to catch him before he buries the gems in a flower bed. During the frantic search for the diamonds, a flotilla of policemen descend upon the Arlingtons' yard. Eventually the diamonds are found by Juanita, but are then snatched away by Dave. After Jerry, who has unearthed an old pistol, fires at the fleeing crooks, the police apprehend the thieves. Declared sane, Jerry embraces Arlene, while Pierre hugs Juanita.