Solving the world's most puzzling mystery novel just got even more fiendish in this gorgeous new hardback collector’s edition – with the final solution sealed in an envelope at the back of the book!Can you crack all the clues and catch the killer before you unseal the ending?'Agatha Christie's masterpiece' SpectatorTen strangers are lured to an island mansion on an isolated rock near the Devon coast- Cut off from the mainland with their generous hosts mysteriously absent they are each accused of