In 1986 Brian Keenan and John McCarthy were forced to take a journey without maps. For the next four years they were incarcerated in a Lebanese dungeon. From the blank outlook of a tiny cell, with only each other and a few volumes of an ancient American encyclopaedia to sustain them, they could only wander the wide open spaces of their imagination. To displace the ugly confines of their existence, they envisaged walking in the High Andes and across...