Sensible Violet Manville and her very ladylike half-sister Sephora are absolutely bored, thank you very much. Though neither of them would ever admit it aloud, they're missing the thrill of playing detective.

So when Violet receives a letter from 'A Heartbroken Mother' sent to her alter-ego, the Agony Aunt known to the world only as Miss Hermione, her pulse can't help but quicken. The daughter in question has gotten caught up in a cult: the Hermetic Order of the Children of Aed. Rumours of human sacrifices, mystical doings, and a ghost in the ruined Alburn Abbey where the Children pray have gripped the public consciousness, helped along by a series of novels about the group, written by the mysterious Count Orlando, and clearly this girl has fallen prey.

Miss Hermione’s investigation soon collides with very real life when Violet discovers a surprising connection to the cult. With the dashing-but-frustrating Eli Marsh turning up and a member of the Children poisoned, Violet and Sephora - along with their ever-trusty housekeeper Bunty - may have more intrigue than they can manage.