Aboard the S.S. American are Billy Crocker, a stowaway in love with heiress Hope Harcourt, who in turn is engaged to Lord Evelyn Oakleigh, nightclub singer and former evangelist Reno Sweeney, and Public Enemy #13, Moonface Martin, who is posing as a minister. A series of comical mistaken identities ensues as the passengers and crew sing and dance their way across the Atlantic.