Ex-child star Posy Starling is finally filming her dream role - Dahlia Lively in The Lady Detective movie. But things take a nightmare turn when a prop weapon is replaced with the real thing - with almost fatal consequences for her fellow Dahlia, Rosalind King. There's something very wrong on the set of The Lady Detective - which means it's time to call in Caro Hooper, so the three Dahlias can investigate. In between filming scenes, signing autographs for locals, photoshoots in London, talk show appearances and jetting off to France for an impromptu party, the three Dahlias do what they do best - surrupticiously sleuth. And very soon the evidence starts to point towards one particular co-star. But before they can prove it, another murder rocks the production. And this time, there are no police to rely on so it's up to the three Dahlias to stop a murderer in their tracks.