When ten-year-old Lewis Barnavelt becomes an orphan, he goes to live with his Uncle Jonathan in the mysterious town of New Zebedee. Expecting nothing more than a quiet caretaker, Lewis instead discovers that his uncle is a well-meaning warlock—and next-door neighbor Mrs. Zimmerman is an even more powerful witch.
 
Their cozy gothic life turns into a race against time when Lewis accidentally resurrects Selenna Izard, a sinister former owner of the house. He learns that the Izards embedded a magical clock deep within the walls—designed to bring about the end of the world. The ticking seems to control reality itself, shifting pace and echoing from unseen places. Now, Lewis, with his caretakers, must use courage and magic to locate the hidden clock and stop a catastrophe.