Mature was worried about the direction of his career at this stage, claiming, "nobody was going to believe I could do anything except grunt and groan." So he went to New York City to try the theatre. He signed to appear in a play with the Group Theatre, "Retreat to Pleasure" by Irwin Shaw. Shortly afterwards it was announced he would appear instead in the musical "Lady in the Dark" with a book by Moss Hart and songs from Ira Gershwin and Kurt Weill; Mature played Randy Curtis, a film star boyfriend of the show's protagonist, magazine editor Liza Elliott (Gertrude Lawrence). Mature later described his role: