An old lady gives Beaver and Wally a tour of the sights of New York City.; Wally and Beaver build a tree house, but the tree may have to be cut down because of elm blight. Wally and Beaver try to find a way to save the tree.; Beaver finds an escaped trained seal in his back yard and keeps it in the bathtub, trying to keep his parents from finding out.; Beaver has trouble building his model airplane.; Beaver gets a skin-diving outfit, but has nowhere to use it.