The world of Ninjago is in terrible danger. An army of skeletons has invaded from the underworld, under the command of the evil Lord Garmadon. Their goal: capture the Four Weapons of Spinjitzu, artifacts so powerful it is said no one being can wield them all at once. Now Garmadon₂s brother, the heroic Sensei Wu, must gather four young men and train them in the ways of the ancient art of Spinjitzu. These four: Kai, Jay, Zane and Cole must become ninja and stand against the dark power of Garmadon.