Robert Louis Stevenson

A French prisoner of war in Edinburgh Castle carves toys for pennies, escapes over the wall, and travels the length of Britain - with a bounty on him, a rich uncle dying in Amersham and a cousin who wants him hanged. Stevenson left this unfinished at his death in Samoa and Quiller-Couch completed it from his notes; the Castle chapters and the flight through the snow are as good as anything he wrote.