A mystery novel by The Detection Club: In 1931 Agatha Christie, Dorothy L. Sayers, and 10 other crime writers from the newly formed Detection Club collaborated in publishing a unique crime novel. In a literary game of consequences, each author would write one chapter, leaving G.K. Chesterton to write a typically paradoxical prologue and Anthony Berkeley to tie up all the loose ends. In addition, all of the authors provided their own solutions in sealed envelopes, all of which appeared at the end of the book, with Agatha Christie's ingenious conclusion acknowledged at the time to be 'enough to make the book worth buying on its own'. The authors of this novel are G.K. Chesterton, Canon Victor Whitechurch, G.D.H. Cole and Margaret Cole, Henry Wade, Agatha Christie, John Rhode, Milward Kennedy, Dorothy L. Sayers, Ronald Knox, Freeman Wills Crofts, Edgar Jepson, Clemence Dane and Anthony Berkeley.