Destined to be yet another classic Halloween-themed episode of THE SIMPSONS, in the opener of the 23rd annual "Treehouse of Horror," we go back to ancient times when a Mayan Homer and Marge are witnesses to the prediction by ancient calendar makers that 2012 will be the end of the world. In "The Greatest Story Ever Holed," the first of three spine-chilling stories, the Springfield Subatomic Supercollider creates a black hole that terrorizes the city, sucking up everything in its path. Then, in "UNnormal Activity" the Simpsons install cameras all over the house when things start to go bump in the night and Marge discovers it may have to do with an unholy pact she made some years prior. In the final thrilling tale, "Bart & Homer's Excellent Adventure," Bart travels to 1974 to buy a comic book at cover price but inadvertently disrupts Homer and Marge's courtship, leading Marge to end up with Artie Ziff .