Karen Brewer's imagination gets the best of her when she decides that her neighbor, Mrs. Porter--who has wild gray hair, wears black robes, and has a garden full of mysterious herbs--must be a witch.
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.
Told that they will have to move out of their Harlem brownstone just after Christmas, the five Vanderbeeker children, ages four to twelve, decide to change their reclusive landlord's mind.
"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"--