Beware of ouija boards, vampires and unexpected guests in the 21st annual installment of the "Treehouse of Horror." In "War and Pieces," the first of three spine-tingling tales, Marge, worried about the effects of excessively violent video games, encourages Bart and Milhouse to give wholesome, classic board games a shot. The best friends discover that board games aren't boring after all when they find themselves playing a real-life game in which they must beat all the challenges before they are allowed to return to home. The supernatural spells continue in "Tweenlight," when Lisa becomes smitten with a mysterious new student, Edmund, who also happens to be a vampire. When a romance blossoms, the young lovers run away to Dracula-la Land, leaving Homer to come to Lisa's rescue. In the final frightening fable, "Master and Cadaver," Homer and Marge set sail on a romantic second honeymoon, but are interrupted when they rescue Roger, a castaway who escaped an attempted poisoning on his ship. Convinced that Roger is sabotaging their getaway and plotting a murder of his own, Homer and Marge take matters into their own hands.

After learning that he is suffering from multiple illnesses and has only a few weeks to live, Mr. Burns becomes distraught by the town's less-than-sensitive reaction to his announcement. Following an unexpected turn of events, Bart finds Mr. Burns weak and vulnerable in the wilderness and secretly takes him into the Simpsons' home. But when Homer and Marge learn about their new houseguest, they decide it's payback time, and Lisa, determined to stand up for Mr. Burns, learns that old habits die hard.