Despite the minimal crime element, Sansom's third Mobile Library mystery (after 2007's Mr. Dixon Disappears
) still succeeds as a light farce. Mobile librarian Israel Armstrong puts his plans to resign on hold when his superiors in Northern Ireland offer him and his irritable companion, Ted Carson, a free trip to London to represent the district at an annual mobile library convention. Armstrong even manages to overcome Carson's initial reluctance by appealing to his pride, betting Carson that their own ratty, aged and broken-down vehicle won't win a prize at the gathering. Soon after arrival in London, the van disappears, and the duo, aided by Armstrong's irrepressible mother, set off on a comic quest to recover it in time for the competition. The book's high point is the acerbic portrayal of the personalities making up the Mobile Library Steering Committee, but most every page will elicit a grin, if not a chuckle. (Aug.)