As Hercule Poirot sifts through his post one particular morning, he alights upon a letter from an elderly and (as it transpires), exceedingly rich spinster - Miss Emily Arundell. She is clearly in great distress and seeking his help, but doesn't say why. Her only specific mention is 'the incident of the dog's ball'.
A lost legacy puts one of England’s great families in mortal peril … Lazen Castle, home to the much-envied Lazender family, is a house under siege. The heir is abroad, pursuing his own adventures, so the family estates fall under the control of his sister, Campion. Meanwhile, The Fallen Angels, a powerful and dangerous secret society in Europe, need the Lazender fortune to bring their rebellion to England.