 Broadway star Patricia Wallis (Evelyn Venable), after a quarrel, leaves the new show produced by Jimmy Hart (Victor Jory) and, not realizing that Hart is in love with her, she runs off to California with the wealthy, stodgy Freddy Arnold (Theodore von Eltz) with the announced intention of getting married. Jimmy discovers that Pat and FReddy will be aboard the crack new "Streamline Express" and he also boards only to become involved in what appears to be a diamond theft. When Jimmy is falsely accused of the  theft" by blackmailer Gilbert Landon (Sidney Blackmier), Pat comes to her senses, precipitating a hasty and starling conclusion to the mystery of the missing diamond.