Movie star Helen Stanley is jumpy, nervous. She checks the gun in her dressing room desk drawer. She calls up her friend Inspector Trent and urges him to come to the studio. By the time Trent arrives, Helen Stanley has been murdered while filming a dance scene. Inspector Trent investigates.
Gail Patrick is only on screen for about 15 minutes as the temperamental Helen Stanley, but that's plenty of time for Patrick to establish her character as one of those mercurial celebrities who race through life making enemies.
It's up to Ralph Bellamy, as Inspector Trent, to sort through those enemies and identify which of them is the murderer. His long list of suspects includes everyone on the set--cameraman, director, bodyguard, crew members. Shirley Grey has a nice role as a script girl who is engaged to cameraman Kane Richmond. Lucien Prival is the veteran movie director, Phillip Trent an assistant, Bradley Page an agent, Ward Bond a crew member--and all seemingly had reasons to do away with the much-hated actress.
Bellamy is fairly low-key as the pipe-chewing Inspector Trent. He offers a few nuggets of detective wisdom ("Those open and shut cases sometimes are the toughest ones to crack") but mainly hangs around the studio asking the obvious questions. That leaves the focus on plot, which along with all of those suspects involves a lost diary and a missing murder weapon. It all moves fairly quickly from one short scene to the next. Overall it's pretty standard, a reliably entertaining B mystery.