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 (Julie Kavner), worried about the effects of excessively violent video games, encourages Bart (Nancy Cartwright) and Milhouse (Pamela Hayden) 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 (Yeardley Smith) becomes smitten with a mysterious new student, Edmund (guest voice Daniel Radcliffe), who also happens to be a vampire. When a romance blossoms, the young lovers run away to Dracula-la Land, leaving Homer (Dan Castellaneta) 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 (guest voice Hugh Laurie), 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.