After a string of films that failed to attract an audience, Sothern left RKO and was signed to MGM, making her first film for them in 1939. In a role originally intended for Jean Harlow, Sothern was cast in Maisie as brassy Brooklyn burlesque dancer Mary Anastasia O'Connor, who also goes by the stage name Maisie Ravier. After years of trying, Sothern had her first real success, and a string of "Maisie" comedy sequels followed, beginning with Congo Maisie (1940) and continuing until Undercover Maisie (1947) in which Maisie infiltrates a gang of con men headed by a phony swami. Reviewing Swing Shift Maisie (1943), Time praised Sothern and described her as "one of the smartest comediennes in the business".