Half" Napoli mourns his dead hat factory worker father while daydreaming of being the first man on the moon and thereby " partaking of something of the infinite." Meanwhile, he and his fellow Back Shop Boys (their fathers all worked in the dangerous, mercury-fume-laden back shops of hat factories) seek to learn the identity of the mysterious Man in Blue, who wanders the town collecting odd items in his rucksack. Elected to spy on him, Half and the mysterious man form a secret friendship in the course of which Half learns not only what " Jack Thomas" has been collecting in his rucksack, and why, but the extraordinary circumstances that led to his fugitive existence -- an odyssey extending from pre-WWII Bohemia to a German POW Camp in Illinois, and beyond.