Denk's list of acting credits begins in the 1930s, with films such as Das verliebte Hotel (1933, as Lilo), Eskapade (1936, as Vera, the bride) and the comedy Peter, Paul und Nanette (1935, as Adele), in which she was described as "a slender brunette, especially attractive as a pert maid" in a 1940 New York Times review.
During this period she also appeared in many stage productions, and was immortalized as one of the stars featured in a now-collectible set of cigarette cards in 1936, along with such popular international stars of the day as Marlene Dietrich and Cary Grant.