Theater distributors were complaining about the time lag between THIN MAN movies, so MGM started a trilogy featuring a husband and wife team of amateur detectives, of which this is the first. In each film different actors played the starring roles (Robert Montgomery and Rosalind Russell in
FAST AND LOOSE, 1939, and Franchot Tone and Ann Sothern in FAST AND FURIOUS, 1939). Douglas is Sloane this first time around, with Rice as his wife. Douglas plays the sleuth, spotting bogus and stolen first edition books and collecting the reward money from insurance companies. When there is a
murder, Douglas searches for and finds the killer.