When Lewis Barnavelt (Owen Vaccaro) is orphaned, he goes to live with his mysterious uncle, Jonathan Barnavelt (Jack Black). Lewis finds to his surprise that Jonathan is a warlock. The house where Jonathan lives was once owned by a couple who were dedicated to black magic. Before they passed away, they hid a clock in the walls with the power to bring about the end of the world.

Lewis and Jonathan have to find the clock before it's too late. 

Based on the 1973 childrens' gothic horror novel The House with a Clock in its Walls by John Bellairs.