Dido Kent's sister-in-law Margaret is attempting to marry her off to the ghastly clergyman Doctor Prowdlee, with his abominable side-whiskers. Dido, however, is determined to refuse him. As punishment she is sent on a journey as companion to her rich, hypochondriac Aunt Manners – whom the family wants to keep on the right side of.

When they arrive at Charcombe Manor, Aunt Manners' childhood home, they find a mystery lying in wait for them. The rich heiress Letitia Verney has disappeared while visiting the house, and Mr Tom Lomax is suspected of abducting her. Dido, upon hearing his story, is inclined to believe in his innocence – but how is she to explain the impossibility of Miss Verney vanishing into thin air?

And there is also the abandoned wing of Charcombe Manor to be considered. Why do lights appear there at night? The house is full of enigmas, with its memories of old family quarrels and its crying ghost that keeps visitors awake. As the mystery intensifies, Miss Dido Kent embarks on her most intriguing investigation yet . . .