+The Earl Carroll Vanities, a popular Broadway revue of the 1930s and '40s, is the setting for this murder mystery interspersed with an assortment of variety acts, including Duke Ellington performing "Ebony Rhapsody" and a novelty number called "Marijuana." Victor McLaglen stars as Bill Murdock, a detective investigating a series of murders during the opening night of a new edition of the +Vanities. When private detective Sadie Evans (Gail Patrick) is found murdered, Murdock must investigate between musical numbers to find the killer. When Rita Rose (Gertrude Michael) next turns up dead, Murdock concludes young ingenue Ann Ware (Kitty Carlisle) is the next person marked for death. Murdock has to find the murderer before the ending of the show or else he or she could disappear in the departing crowd of theatergoers.