As the episode opens, Mayor Goodway and Chickaletta are busy cleaning up litter around the front area of City Hall as part of the Tidiest Town Competition, when who should show up to gloat again, but Goodway's arch-rival, Foggy Bottom Mayor Humdinger, believing his town will win once more, even taunting Goodway by tossing a piece of litter away, only for Chickaletta to quickly retrieve it. As Goodway and Chickaletta head off to continue looking for litter, once they are out of earshot, Humdinger decides to teach Goodway a lesson, and summons his secret weapon: The Kitten Catastrophe Crew, six kittens decked out in uniforms, gear, and similarly identical in appearance to that of the PAW Patrol, but with the logo on their hats and tags being that of a cat's head with mean-looking eyes.
With the aid of his evil versions of the PAW Patrol, Humdinger wrecks the front yard of City Hall, before recalling the kittens and hiding behind the hedges to await the aftermath of their sabotage. When Goodway returns, she's horrified by the destruction. Unable to find out what caused it, she decides to dial up Ryder and let him know of the situation with the effort to win the Tidiest Town Competition.
At the Lookout, the pups are enjoying jump rope, until Marshall once again gets himself tied up by the rope itself when he missteps his jump. Ryder laughs from the Lookout balcony until he gets Goodway's call for help regarding cleaning up City Hall and finding out who's responsible for the damage. Ryder agrees and summons the pups.
When Marshall is untied from the jump rope, he ends up spinning away like a top, ricocheting off of several of the pup houses, pillows, and snack dispensers like a pinball, before coming to a rest in the elevator, which tallies up his score, leaving the pups to state that Marshall got the high score, leading to all of them laughing about it afterwards as they head topside. Once there, Ryder explains the situation, and passes out orders: Chase will use his Super Spy gear to figure out who caused all the sabotage that might cost Adventure Bay the trophy for Tidiest Town, while Rocky and Rubble will help clean up all the trash, recyclables, and replant the flowers. The team deploys, and once at City Hall, get right to work. However, as they clean up, Humdinger attempts to prolong their efforts, which only serve to raise Chase's suspicions when his cat allergies are affected by the scent left by Humdinger's kittens.
Soon, once at Mr. Porter's restaurant, Chase spots Humdinger and his kittens from the restaurant's roof, thus proving his suspicions, as Marshall's kitten counterpart temporarily blinds Chase with mud on his infrared goggles. As Chase spots them planning their next move, although Humdinger corrects him on what he just said out loud, he attempts to intercept Humdinger via his zip-line, only for Humdinger to have Rocky's kitten counterpart disconnect it, sending Chase falling safely into Ryder's arms.
Soon, Humdinger is at the water tower, attempting to open the valve and saturate the ground with the stored water inside it. Marshall and Rocky try to intercept him, but Rocky's kitten counterpart manages to open the valve, despite Rocky ordering him to back off, and douses Rocky with water, much to his chagrin. However, karma catches up to Humdinger as he prepares to flee, as he slips and slides off the top of the water tower and is left hanging on to the edge for dear life. With Chase and Ryder's help, Humdinger is lowered to the ground safely on Chase's zipline, while Marshall readjusts his ladder to get Rocky out from under the faucet and up to the valve to close it and save what water is still in the water tower.
Afterwards, Humdinger is somewhat humbled at how the pups who always managed to beat him and Foggy Bottom in various competitions were able to save his life, and confesses to his actions against Mayor Goodway and offers his thanks and apology. However, Ryder suggests that if Humdinger is truly grateful and sorry for what he's done, he and his kittens won't mind helping with cleaning up the mess they caused. Faced with that, Humdinger begrudgingly agrees with an annoyed grumble, and while he and his kittens clean up the area in front of City Hall, somewhat unhappily, the judge awards the trophy for Tidiest Town to Mayor Goodway, who then gives it to the PAW Patrol since they helped win it together.
Marshall gives everyone a laugh to end the episode as he peers inside the trophy, and sneezes loose all the dust collected inside, much to everyone's amusement.