Homer is upset when he realizes that Marge brought him and the family to a boring Harvest Fest instead of his much-anticipated day of debauchery at October Fest. Attempting to leave, Homer accidentally drags the family into a puzzling cornfield maze. When the whole family manages to escape except for Homer, they send out Santa's Little Helper, who sniffs out Homer and rescues him. Santa's Little Helper becomes a local hero and the Simpsons decide to enroll him in Police Dog Academy, where he's teamed with a grizzled veteran cop named Lou and they become a crime-busting duo. Bart's excitement quickly dissipates when a jaded Santa's Little Helper bites him, and the Simpsons send the dog away to live with Chief Wiggum. To appease Bart's depression after the loss of his dog, Marge agrees to buy him a huge pet snake. But when the snake causes a life-threatening situation at Bart and Lisa's school, Santa's Little Helper gets a chance to redeem himself.

At the Simpsons' annual dental check-up, Lisa gets an education in dental hygiene from a video starring Ludacris (guest voice Chris "Ludacris" Bridges) as Luda-Crest, a tube of toothpaste with a talent for rapping. The Simpsons stop for ice cream on the way home from the dentist, and when Homer purchases the 1-millionth ice cream cone, he is featured on Kent Brockman's nightly news program. However, the innocent interview turns into trouble when Brockman uses a shocking expletive and Ned Flanders wages an anti-indecency campaign. The Simpsons take in the dejected Brockman, and he and Lisa begin to devise a scheme for the anchor to make his comeback. Meanwhile, Principal Skinner ushers the students of Springfield Elementary into a new era of sneaking, snooping and snitching with the opening of the school's CTU Counter Truancy Unit with Lisa heading up the operation. Homer is sent on a mission to dispose of a container of yogurt so far past its freshness date that it could be toxic, but the reeking yogurt falls into the wrong hands. With the help of Jack Bauer (guest voice Kiefer Sutherland) and Chloe O'Brian (guest voice Mary Lynn Rajskub), Bart and Lisa must stop bullies Dolph, Kearney and Jimbo from releasing the ultimate stink bomb at the school's annual bake sale.