In the 1920s Bright Young Things are famous for treasure hunts that were a media obsession. One such game takes place at the 18th birthday party of Pamela Mitford but ends in tragedy as Adrian Curtis meets his death. The police quickly identify the killer in Dulcie. But Louisa Cannon, chaperone to the Mitford girls, believes Dulcie to be innocent, and sets out to clear the girl's name. Soon to be a major TV drama from the makers of "The Crown".