It's the annual Mayor's Race and Mayor Goodway is determined to give it her best. Mayor Humdinger is determined to give it his best too; his best cheating devious scheme yet. Mayoral contestants need to row a boat, swim and then run a foot race to the finish line! The pups are busy, they need to help Mayor Goodway train, and clean up Mayor Humdinger's disasters. First, Rocky fixes a hole that mysteriously appeared in Mayor Goodway's boat. Chase is on the case as he stops the Kitten Catastrophe Crew from pouring corn oil all over the race route while Skye helps rescue Mayor Humdinger who gets caught up in his own foul schemes. Cheaters never win!
While Rocky helps Ryder with his ATV, down on the beach, Mayor Humdinger and his Kitten Catastrophe Crew are at it again, sabotaging their rival mayors from competing in the Annual Mayor Triathlon, with Mayor Goodway being their latest victim as Humdinger has Rocky's kitten counterpart drill a hole into Goodway's boat, leading to it slowly sinking during Goodway's training session later.
Luckily, Zuma arrives to push Goodway back to shore, but as the Mayor frets not being able to win the Triathlon, Chase reminds her to call Ryder for help. The Mayor does just that, and Ryder summons the pups. Marshall gets flung out of the hammock he's in and flies and rolls into the elevator, crashing into the pups, save Skye, along the way, before they join him and head topside.
Once there, Ryder explains that Mayor Goodway needs their help to train for the Triathlon, and assigns Chase to train her in the running portion while having Rocky fix her boat for the rowboat leg. The team deploys, and Marshall joins the Mayor in helping her build up her stamina for the running leg of the race. Meanwhile, after Rocky repairs the rowboat, Chase's allergies go off, indicating that the scent of kittens is nearby, arousing Ryder and Chase's suspicions that Humdinger might be cheating...
The next day, the Triathlon begins, with Goodway, Humdinger, and three other mayors being the competitors. As the rowboat portion begins, Humdinger finds himself falling behind, so he uses Zuma's kitten counterpart to covertly take the lead and win the first leg. During the second leg, the swimming portion, when Humdinger again finds himself falling behind, he signals Chase's kitten counterpart to launch sardines into the water, attracting dolphins to inhibit Goodway and the other mayors, allowing him to win the second leg. Unfortunately for him, Chase's allergies alerted Ryder to spot his kitten counterpart, confirming his suspicions that Humdinger was cheating all along. Knowing that the Catastrophe Crew will plan on sabotaging the third leg, the running portion, as well, Ryder summons Skye to provide overwatch for the last leg and Chase to intercept them if he sees them attempt to do so.
As the third leg gets underway, Chase soon spots the Catastrophe Crew attempting to slip up Goodway and the other mayors with oil, and apprehends them before they can. With the Catastrophe Crew under arrest by Chase's paws, Humdinger resorts to using the carrier the Catastrophe Crew ride in to take the lead via a shortcut out of sight of the other mayors. Skye spots him, but karma beat her to Humdinger when he wasn't looking where he was going before the carrier hits a log and flings him off into a nearby gorge, leaving him hanging for dear life from a protruding tree branch.
Luckily for him, Skye spots him and notifies Ryder and Chase, who arrive and lift him to safety with Chase's winch. Humdinger is grateful for the rescue, but Ryder reminds him of the famous creed of "Cheaters never prosper" as since Ryder knows Humdinger cheated, he will be disqualified from the Triathlon. Humdinger grumbles in defeat as Ryder, Chase, and Skye head to the finish line to watch Mayor Goodway win the race.
Mayor Goodway crosses the finish line first, winning the third leg, and since Humdinger was disqualified for cheating, she wins the first two legs by default, making her the winner of the Triathlon. Mayor Goodway is grateful to the PAW Patrol for their help, and everyone shares a good laugh to end the episode.