The movie is based on the 1973 novel of the same name by John Bellairs.
In 1953, ten-year-old Lewis Barnavelt goes to New Zebedee, Michigan to live with his uncle Jonathan in a creaky old house which has a mysterious ticking heart. Recently orphaned, Lewis only wants to have a normal childhood but soon discovers he's in line for anything but that. Uncle Jonathan is in fact a mediocre but well-intentioned warlock, while his next-door neighbor and good friend Florence Zimmerman is a far more powerful good witch. The house that Lewis has just moved into was previously owned by Isaac and Selena Izard. Before dying, this sinister couple had constructed a powerful clock that is hidden somewhere within the walls of the house where it ticks eternally, trying to pull the world into a magical alignment that would have permitted Isaac to bring about the end of the world. But the sleepy facade of Lewis' new town jolts to life with a secret world of warlocks and witches when Lewis, wanting only to make a new friend and impress the popular Tarby Corrigan, attempts to raise the dead in the local cemetery on Halloween and succeeds in accidentally releasing Selena from her tomb. Things quickly go awry as the sorceress' ghost and a horde of fantastical creatures are soon unleashed to wreak destruction on the town. Now, with the help of Jonathan and Mrs. Zimmerman, Lewis must summon all his courage to prevent the evil sorceress Selena from finishing her husband's work, and attempt to contain the growing supernatural forces of evil that threaten to bring about Doomsday for the whole world.