Walter Higgins is a scrappy child with a great imagination, yet is still not quite sure of himself. In fact, he feels lost when he is shipped off to Boston to visit his unknown Great Aunt Hortensia (“the Warden”) while his parents pursue their own dream of climbing Mount Kilimanjaro. Walter feels he is in for the worst summer ever. But then he befriends a mysterious neighbor, Old Zeb, a lonely, grizzled sailor who builds ships in bottles. Deep in the cavernous confines of the cellar, Old Zeb lets Walter in on the Great Secret Project and his lifelong dream.