When her contract expired in 1937, Marsh once again freelanced, appearing steadily in movies for RKO Radio Pictures, where she made "Saturday's Heroes" (1937) with Van Heflin, and for Paramount Pictures, where she played a young woman caught up in a mystery in "The Great Gambini" (1937). She appeared with comic Joe E. Brown in "When's Your Birthday?" (1937), and Richard Arlen in "Missing Daughters" (1939). In the 1940s, Marsh played Wallace Ford's secretary in "Murder by Invitation" (1941) and the self-willed wife in "Gentleman from Dixie" (1941). In her last screen appearance, Marsh portrayed the daughter of an inventor in the comedy/mystery "House of Errors" (1942), which starred Harry Langdon.