Who Killed Robert Prentice?

12 Dec 1936 - 31 May 1937 What is the significance of the railway ticket found in the cottage where the victim met his mistress, the lovely Suzanne L'Estrange? Why was a Belgian stamp found in the hall? Why did Robert Prentice write such a vindictive letter to Miss L'Estrange, and what was the fatal outcome? What did the blackmailer see through the bedroom window, and who tore up his photograph? Test your powers of deduction when you break the sealed section containing the NAME OF THE MURDERER.