Never pick up hitch-hikers! - Ellis Peters

When Alf Jarrett spots the hitch-hiker, he thinks his prayers have been answered. William Banks is a personable young man of twenty, leaving home for the first time - and perfect for what Alf has in mind. William eagerly accepts Alf's offer of a free night's lodging and the chance to repay him for the lift, but he doesn't realise that in following Alf's instructions he is made the intended victim in a sinister plot of arson and murder. Only William's good fortune - and the timely intervention of a guardian angel in the form of a charming girl called Calli - saves him from becoming a corpse. Suddenly, William and Calli find themselves thrown into a case involving mistaken identity, bank robbery and murder, and they aren't the only ones on the trail...