Sensei Wu awakes in the Underworld, his journey having knocked him out. He begins to search for Lord Garmadon. Zane, Cole, and Jay arrive at the Fire Temple, but Zane's sixth sense tells them that all four weapons are now in the Underworld, and that Kai and Wu have failed. Cole admits with a sigh that they have been defeated, and that there's no way now to regain control of the weapons. He is proven wrong in several moments, as Kai and Nya appear aback the Fire Dragon, whom now fully understands the situation and has the ability to cross to the Underworld.
Cole points out that there's no way for all of them to fit on the one dragon. Kai has a solution, returning to all three of the other elemental dragons. The dragons pass to the Underworld, and the four Ninjas attempt to silently sneak into Garmadon's Fortress. Swinging from stalactites, the Ninjas are close to their goal when Jay, still speechless, notices that they are actually hanging from the legs of Bone Spiders. Unable to receive his warning, the four plummet to the ground, where Nuckal raise the Ninja Alarm.
Jay is able to gain usage of his voice back in time to remind the others of the Tornado of Creation, which they successfully attempt, turning the fortress into a caged Ferris wheel and entrapping the skeletons inside it.
Meanwhile, in Lord Garmadon's throne room, Sensei Wu has used the Sword of Fire to destroy a group of skeletons, stating that Garmadon will have to take the Sword from him. Garmadon calls on Samukai, who now holds the Shurikens, Nunchuks, and the Scythe. The four Ninjas arrive to witness the battle, but choose to let Wu fight Garmadon on his own. Samukai defeats Sensei Wu and obtains the Sword.
He turns on Garmadon, keeping all the power for himself, but is unable to contain all of the energy streaming through him. The weapons fuse and disintegrate Samukai, in the process opening a time portal to the Overworld. Garmadon jumps through the portal and escapes the Underworld, but not before promising to one day wield all four weapons and use them to recreate the world in his image.
Though Garmadon is gone, Wu sighs and states that he will one day return, perhaps with the power to do as he pleases. The four Ninjas pick up the golden weapons, now lying on the ground. Turning to Wu, Kai says "And we'll be ready for him". They return on the dragons to the blacksmith shop and reunite with Nya, becoming heroes across Ninjago.thumb|300px|right