The episode starts presenting the ordinary intro as typical, with Bart writing on the chalkboard (which reads ¨Thanks for 28 great years...Taylor Swift¨). But the scene immediately cuts to Homer driving down the street. Homer tosses the radioactive bar out the window as usual, and gets caught in a traffic jam. He then almost mows down several people by cutting through the lanes. Next, he careens into an alley without any room to maneuver and too late to use the brakes, where Santa's Little Helper and the now-homeless Gil are eating out of trash cans. Homer is terrified by the prospect of running over a sweet and lovable dog, so he slams into Gil instead, who sustains a serious neck injury and plans to sue the Simpsons for everything they have.
The jury accepts the defense objection that dogs are not only as good as humans, but better in lots of ways, and they dismiss Gil's case. Mayor Quimby chooses to ride the wave of pro-pooch sentiment, instituting measures that cater to dogs and punish humans involved in activities that can be perceived as anti-canine, such as dogcatchers. Even the town Veterinarian Dr. Budgie is arrested and put into shackles.
Dr. Budgie predicts that the dogs will soon realize that humans have abdicated their status as alphas, something he warns will lead to them turning on the citizens of Springfield. However, he is not taken seriously until it actually happens. Even Santa's Little Helper joins the feral dog pack, as the town takes shelter from the now-vicious dogs, and a meeting leads to the community begging for their most broken-down citizen to help them: Gil. Gil is prepared to stand up to his fellow street creatures, but it is Marge who steps up, and after finding out that the leader of the dog pack is a wild chihuahua named Taquito, kicks the hound from their showdown park and becomes the new alpha of Springfield.
All of the dogs are reunited with their owners, from Ned's puppy Baz and Mr. Burns' hounds, to Lisa and Bart's joyous reunion with Santa's Little Helper.
In the final scene, Gil thinks that he has found a new friend with the weakened Taquito, which licks Gil's face and barks happily. Gil doesn't realize the hound is only being friendly so he can get a taste for Gil before he finally passes on and Taquito eats his corpse.
