Young Randolph has two favorite pastimes -- hockey and collecting. When his family rents out part of their house, Mr. Karp takes over two rooms on the third floor, and Randolph soon learns that the new boarder is a collector too.
It turns out that Mr. Karp collects water -- samples that he keeps in glass containers, each one carefully labeled: Ditch water from St. Louis, Missouri, after the tornado of 1896. Pitcher used by Benito Mussolini to throw water in face of army private during tantrum, 1941. Randolph is astonished to learn that Mr. Karp is just one of many water collectors, and the only thing preventing him from being the foremost water collector in his region is a rival named Ravelson. To beat Ravelson, Mr. Karp heads to Japan to obtain a unique sample -- melted snow taken from the upturned hat of Napoleon Bonaparte during the Russian campaign.