London, 1893: James Norbury is a shy would-be poet, newly down from Oxford and confounded by the sinister, labyrinthine city at his doorstep. Taking up lodging with a dissolute young aristocrat, he is introduced to the drawing rooms of high society and finds love in an unexpected quarter. On the cusp of achieving a happiness long denied to him, he vanishes without a trace. His sister Charlotte sets out to find her brother. Her search leads her to one of the country's pre-eminent and mysterious institutions: The Aegolius Club.