After narrowly escaping an ancient burial ground, long forgotten and buried underneath the marshes of Cape Cod, a group of friends emerge from the thick, marshy darkness, tattered and bloody, lucky to be alive. They have already lost two of their friends in the marsh, presumably dead. They stumble upon an empty Cape Cod vacation house alongside the foggy marsh and break in to take shelter. Whatever was in the marsh is still after them and soon after one of them goes for help, the rest of the group learns that the evil in the marsh is not the only thing that wants them dead. Something worse, something more savage, was lying in wait just outside the marsh, in the house. What happens next is unspeakable, horror that cannot be unseen. These unlucky travelers spend their St. Patrick's Day trapped between two evils forcing them to fight, die, or go back the way they came.

A shocking family portrait. A boy oozing blood and saliva, bound by ropes and handcuffs, imprisoned in an animal cage. A deeply religious mother who believes her son is controlled by the devil. A Catholic priest devoted to saving his family, who tries to cure his deranged younger brother - but 13-year-old Jimmy Morgan is possessed by an evil too powerful to be exorcised by any religion. After escaping from a mental institution, Jimmy is back with a vengeance - and an army of children who follow his every murderous desire. The town trembles in fear as the youths attack and abduct its residents - innocent and guilty alike - dragging their victims to an abandoned castle and subjecting them to grisly torments deep within its underground tunnels. Those who discover the terrible secret behind the disappearances and deaths don't live long enough to tell it. The teacher, the doctor, even Jimmy's own brother and mother, will all confront their fates in the Torture Chamber.