Henry's life changes dramatically after his parents are kidnapped. He leaves Boston, where he lived a sheltered life, and moves in with his Aunt, Uncle and their children in Kansas, where he can roam freely and even ride in the open cab of his Uncle's truck. Henry is given a cozy room in the attic, which has a secret waiting for him to discover. When pieces of plaster begin to fall from the wall, Henry finds hidden cabinet doors in all shapes, colors, and sizes. With his cousin, Henrietta, they discover that each door leads to a different world.
The story begins on the slow side, but the excitement picks up once Henry and Henrietta begin wandering through the different worlds. You can find the list and a drawing of the cabinets at the beginning of the book.