Catboy realizes being the best isn't always the solution when the PJ Masks have to prevent Night Ninja from stealing a magical ring hidden atop the Mystery Mountain. Catboy, Gekko, and Owlette have to get into the Mystery Mountain to retrieve a magical ring for Night Ninja, who captured PJ Robot. As Rip and Howler are tagging the city with paint, Kevin starts to have second thoughts about being a mean one.

Raph, Leo, Mikey, and Donnie are becoming the heroes they are destined to be. But nothing can prepare them for what they face on, and below, the streets of NYC, where they discover a hidden mystical world and wield brand-new, powered-up weapons. The Turtles face formidable foes, battle bizarre mutants, wrestle a heavyweight champ, and still make time for the best pizza in the city!

The young Master Builder Lloyd, aka the Green Ninja, along with his friends, that are all secret ninja warriors. Led by Master Wu, is wise-cracking as he is wise, they must defeat evil warlord Garmadon, who also happens to be Lloyd's dad. Pitting mech against mech and father against son, this showdown will test this fierce but undisciplined team of modern-day ninjas who must learn to check their egos and pull together to unleash their inner power...