Book excerpt: This early work by Richard Austin Freeman was originally published in 1936 and we are now republishing it with a brand new introduction. 'The Penrose Mystery' is one of Freeman's novels of crime and mystery. The first story featuring his well-known protagonist Dr. Thorndyke - a medico-legal forensic investigator - was published in 1907, and although Freeman's early works were seen as simple homages to his contemporary, Sir Arthur Conan Doyle, he quickly developed his own style: The 'inverted detective story', in which the identity of the criminal is shown from the beginning, and the story then describes the detective's attempt to solve the mystery.