Sunny was one of three RKO Radio Broadway-musical adaptations tailored to the talents of British favorite Anna Neagle by her soon-to-be-husband Herbert Wilcox. The story has been updated a bit and transposed to New Orleans' Mardi Gras, but remains at base a "Cinderella" yarn, replete with a poor girl/rich boy romance. Circus entertainer Sunny Sullivan falls in love with Larry Warren, wealthy scion of an auto-manufacturing family. Accepting his invitation to meet his family at a fancy weekend party, Sunny elects to hide the fact that she's in show business. Just as she's won over the entire family, who should arrive but her circus cohorts, immediately blowing her cover. The shamefaced Sunny returns to the big top, but Larry will not be dissuaded from his intention to make her his bride.