Here's what happened according to snpp.com:
Bart stumbles onto an advertisement for a rap concert in Springfield starring Alcatraaz (when Santa's Little Helper swallows the remote control and changes channels every time he barks). However, Marge refuses to let him go, so he sneaks out of the house; at the show, he busts a rhyme on Homer, and gets a ride back home from the star. Before he can get inside, he hears Marge and Homer vent their anger over his disobeying them, so he writes a kidnapping note and throws it into the house. Chief Wiggum announces he is on the case, to the amusement of everyone at the press conference; later, he realizes that he hasn't exactly been the best policeman out there. Bart needs a place to hide, and finds it in Kirk van Houten's apartment; he makes a call to Homer disguising his voice, but Wiggum hears something in the background; a rather cheap type of stove-popped popcorn that only he and Kirk buy. The police storm Kirk's apartment, find Bart (who was hiding there without telling Kirk about it), and arrest Kirk. The arrest gets Wiggum promoted to police commissioner, and Kirk gets thrown into a jail cell, which is not only cleaner than his apartment, but he gets three meals a day and an hour with his "groupies" (consisting of pretty much every older single female in Springfield except Mrs. Krabappel). One small problem: the truth - uncovered by Lisa when she finds the basketball jersey Bart got from the concert. She and Principal Skinner go to Alcatraaz's home and see the tape of the concert. Just then, Wiggum and Homer come in and want the tape. Lisa thinks the truth is more important, even though nobody is being hurt by the lie. Alcatraaz has the solution: house par-tay!