It's night in the park, and Night Ninja and his Ninjalinos are working on a new Sticky Splat. Then the Wolfy Kids show up and demand that the ninjas leave. Instead, Night Ninja orders his Ninjalinos to attack the Wolfies with the new sticky splat. A sticky splat projectile lands in Kevin's hair, and when Rip pulls it off, she also pulls out some of Kevin's fur. Rip throws the splat, with the fur still glued to it, back at the Ninjalinos, and hits Marvin. To everyone's surprise, Marvin promptly transforms into a werewolf-like Ninjalino, and runs off to join the Wolfies.
The following day Connor, Amaya and Greg visit the park, where they find the remains of the fight from last night. Surprised by the fourth set of wolfy footprints, they decide to investigate. So that night, they transform into the PJ Masks and scout the park with the PJ Rovers. They find the transformed Marvin, whom Catboy dubs a Werejalino.
Both the Wolfies and Night Ninja with his remaining Ninjalinos show up and get into a fight, with the PJ Masks stuck between both groups. While the PJ Masks try to limit the damage, the other Ninjalinos get ahold of Marvin. They take the sticky splat with Kevin's fur from him, and use it on themselves and thus become Werejalinos as well. They all abandon Night Ninja and join the Wolfies.
The Wolfies leave the park, and Night Ninja angrily teleports away in a puff of smoke. The PJ Masks chase the Wolfies and Werejalinos to Mystery Mountain. Kevin briefly gets stuck in a puddle of sticky splat, but one of the Werejalinos frees him using Ninja Fingers. At the top of the mountain, Night Ninja confronts the Wolfies again, but he's hopelessly outnumbered and can't stop the Wolfies from entering the pagoda. Catboy saves Night Ninja from one of the Pagoda's booby traps, but then the Werejalinos and Wolfies accidently activate the other traps. Soon, the PJ Masks and Night Ninja are all trapped in sticky splat, while the Wolfies are ensnared by the dragon tongues, leaving only the Werejalinos free.
Both Night Ninja and the Wolfies try to convince the Werejalinos to free them, but the Werejalinos clearly don't know who to listen to. The PJ Masks suggest Night Ninja to be nice to his henchmen for once and remind them how much fun it is to be a ninja. They free themselves from the Sticky Splat using various ninja attacks, and Catboy appologizes for treating the Werejalinos like dogs. It works and the Werejalinos transform back into Ninjalinos. They proceed to use their ninja fingers to send the Wolfy Kids off Mystery Mountain.
Night Ninja, who is still trapped in the sticky splat, demands the Ninjalinos free him, but they refuse. Gekko once more points out that Night Ninja really should be nicer to the Ninjalinos. Night Ninja refuses, so the Ninjalinos roll him onto one of the booby traps and catapult him out of the pagoda. The Ninjalinos follow him, while the PJ Masks celebrate their victory.