World War I is over, and the American soldiers are boarding ships to sail for home. Pvt. Charley Chase smuggles his French girlfriend Antoinette aboard as a bag of dirty laundry while his pet monkey Napoleon manages to sneak aboard on his own. Charley and his monkey steal a soldier's uniform for Antoinette piece by piece, and then Charley sings, dances, plays the harmonica and accordion, and pulls pranks on his fellow soldiers while he should be working. The ship's doctor attempts to restore the beautiful tenor voice of a member of Charley's quartet, and Napoleon wreaks havoc by playing with the ship's controls and a cannon.