In the bustling high-tech city of Ninjago, young Lloyd and his friends, all of whom are secret ninja warriors led by Master Wu, defend their city from the frequent attacks of the evil warlord Garmadon. However, Garmadon is not just any villain; he is also Lloyd's estranged father, which makes their confrontations emotionally complicated. Despite Garmadon's relentless assaults, the citizens of Ninjago idolize the ninjas for their prowess and heroism, even though they remain unaware of their real identities. Lloyd, in particular, struggles with his dual life—a high school student by day and a green ninja and de facto leader of the group by night.

Amid this struggle, the ninjas use their elemental powers and impressive mech vehicles to thwart Garmadon's schemes. Following a battle that does not go as planned, the team embarks on a journey to find the Ultimate, Ultimate Weapon, guided by Master Wu. They must learn to trust each other and work as a cohesive unit as they face various obstacles and challenges along the way. The ninjas' quest also leads to personal growth and self-discovery, especially for Lloyd, as he learns important lessons about the power of teamwork, the importance of openness about one's true self, and dealing with the complexities of a fractured family.