The Crime at Black Dudley by Margery Allingham

A house party is under way at the remote mansion of Black Dudley, and among the guests are some very shady characters. As they playfully recreate the ritual of the Black Dudley Dagger, someone dies. Pathologist George Abbershaw suspects foul play, and when a vital item is mislaid, a gang of crooks hold the guests hostage. Will they escape the house – what did happen to the Colonel – and just who is the mysterious Mr Campion? Neither the story nor Albert Campion is quite as vapid and slow as you might expect....apa in US as THE BLACK DUDLEY MURDER, 1929