This is the fourth book in Bellairs' Lewis Barnavelt series and was completed after Bellairs' death by Brad Strickland. Strickland did a good job staying true to Bellairs' characters and put together a very engaging story.
While this is a Lewis Barnavelt story, Lewis and his uncle Jonathon are bit players in this tale.
Rose Rita and Mrs Zimmermann embark on a trek to restore Mrs Zimmermann's lost magical powers. They find themselves transported back in time where they must right a past wrong. Doing so pits them against a local wizard with a grudge and a generations old score to settle.