As they look forward to the New York City Marathon in which their friend Mr. B. will run, the Vanderbeeker children learn that one of their good friends is homeless.
"When catastrophe strikes their beloved upstairs neighbors, the Vanderbeeker children set out to build the best, most magical healing garden in Harlem--in spite of a locked fence, thistles and trash, and the conflicting plans of a wealthy real estate developer"--
Excited for Papa's surprise fortieth birthday party, the Vanderbeeker children learn more about their mysterious grandparents while waiting for the celebration to start.