William has used the magical Janus medal to shrink Mrs. Phillips, his beloved nanny, down to the size of his index finger. He thinks this is the only way to keep her from leaving him and returning to her home in England. William takes her to the attic to live in a magical toy castle.
Sir Simon who also lives in the magical castle has lost his kingdom to the evil wizard Alastor. He asks William to shrink himself, so that he can go on a quest to not only help Sir Simon defeat Alastor but to retrieve the second half of the Janus medal so that Mrs. Phillip can return to her normal size. Will William be able to defeat the evil wizard Alastor, help Sir Simon, and return Mrs. Phillips to her normal self? Read The Castle in the Attic by Elizabeth Winthrop to see if William is successful in his quest.