Murder with Mack and Mabel: Lovesey, master of the period-mystery invention, now drenches a so-so plot in early-moviemaking lore, making his sleuth an English vaudevillian who has (reluctantly) taken a job as one of Mack Sennett's Keystone Cops. This narrator/hero is Warwick Easton, who--observing the Sennett operation on his first day at work--sees a Keystone Cop accidentally killed while doing a tricky stunt. Upsetting. . . but Easton is soon more preoccupied with lovely Amber Honeybee, an ambitious but virginal no-talent whom Sennett has, for unknown reasons, given a lead role. (Has Mack dumped Mabel Normand for Amber?) Then there's another ""accident"": Amber's sweet mother dies from a fall. . . or a push? And why is someone ransacking Amber's house, roughing up Easton? What are they looking for? Could it be a piece of unexposed film in Amber's possession? Easton ponders all this, especially after Amber disappears, all her hair turning up in his motorcar trunk. (The real cops naturally suspect him of murder.) The mystery-film is developed--and it seems to involve that stunt-accident. Was Sennett being blackmailed by Amber? Well, yes--though the murder motives (a cameraman also turns up dead) lies elsewhere. An uninspired puzzle--but Lovesey does a suave, amused, uncluttered job with the gritty silent-screen backgrounds, the many early-Hollywood cameos, and the camera/technical details.