Funny lines are fairly common in thrillers, but novels that are both thrilling and comic are few and far between. This is one of the rare examples of that difficult balancing act. Miller, an amiable but conventional naval officer, finds himself assigned to the most disreputable tramp steamer in WWII Malta, as part of a Royal Navy scheme to confound the Germans. The crew, he quickly discovers, is of a piece with the ship: the bos'un is nearly blind, the mate is a borderline psychopath, and the captain seems to have stepped out of a pirate movie. Callison deploys these cartoonish characters to great comic effect, all the while keeping a respectable thriller plot chugging along. ( )