Ben and his younger sister Saoirse live with their father Conor in an isolated lighthouse. Their mother died six years ago while giving birth to Saoirse. Unable to talk, Saoirse is starting to show special powers and sea creatures seem to respect her, indicating that she is no normal little girl.

The battle for Ninjago City calls to action young Master Builder Lloyd, aka the Green Ninja, along with his friends, who are all secret ninja warriors. Led by Master Wu, as wise-cracking as he is wise, they must defeat evil warlord Garmadon, The Worst Guy Ever, who also happens to be Lloyd's dad.