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Jay takes Nya back to her and Kai's family shop to pick up some things for her move into the Monastery of Spinjitzu. While she is alone, a pair of Skulkin attack her, but she easily defeats the hapless skeletons.
Flight of the Dragon Ninja
At the Monastery, Jay is trying to convince the Ninja that he was the best out of them all after having won in a race with their Dragons beforehand. They decide to hold another race, although Zane objects, claiming they should be training instead, to which Kai assures him that riding their Dragons is a form of training.
They head out on their Dragons and Cole sets the terms of the race, telling them that whoever wins the race will be Dragon Master for a month. Kai and Zane get into a bit of a scuffle on their Dragons, before Zane takes the lead. Cole and Jay speed through the forest below, attempting to dodge the trees until the Earth Dragon smashes into one, snapping it in half and continuing on. The group approaches the "finish line" but Cole speeds across by dangling a roasted chicken on a rope in front of Rocky's nose. Cole lands first, but Kai tells him they'll beat him the next day. Cole protests that they agreed the winner would be Dragon Master for a month, but Zane claims not to recall ever agreeing to that.
The New Masters of Spinjitzu
Kruncha and Nuckal are in the Underworld complaining about how the Ninja came down and ruined everything. Kruncha then comments on how "they wouldn't be so tough without their magic weapons," giving Kruncha an idea. The pair then travels to the Monastery and steals the Golden Weapons as the Ninja sleep. However, when Nuckal shakes the Nunchucks of Lightning he loses control of the weapon and by mistake activates the training course, flailing about in a Spinjitzu tornado.
After Kruncha loses control of the Sword of Fire, the two begin to fight, but stop when a half-asleep Kai comes out and turns off the training course. Kai yells to Jay that the training course turned itself on again and for him to fix it, to which Jay replies that he'll fix it the next day.
The two Skulkin Generals then slip the weapons back into their places and sneak out, arguing over whose idea it was, and blaming each other for ever considering such a stupid idea to begin with.
An Underworldly Takeover
Cole asks Sensei Wu how Lord Garmadon had control over the Skulkin, Wu tells him that him and Garmadon used to be friends before he fell. A flashback then shows Garmadon after he fell into the Underworld, then Samukai and his skeletons close in on him. Garmadon then fights Samukai and uses Spinjitzu to win, he then takes Samukai's helmet and claims the title "King of the Underworld". It is then revealed Wu doesn't know how Garmadon became leader and then thinks they "Talked it over a nice cup of tea".
Return to the Fire Temple
Kai and Nya are out on a flight with Flame when the Dragon suddenly takes a detour, flying down to the Fire Temple. Once landed, Flame nudges Kai along and Nya comments that the Dragon must want to show them something, soon revealing to them a secret entrance leading to the Underworld overrun with Skulkin. Kai accidentally falls down a small cliffside, alerting the Skulkin to his presence. Wyplash commands the Skeletons to attack, and Kai uses the Sword of Fire to quickly disarm them, but they pick Kai up afterwards, causing him to drop his weapon. Kai attempts to use Spinjitzu to shake the Skulkin warriors, but to no avail. Nya then flies in on Flame to help Kai, but he denies that he needs it, claiming he's simply formulating a plan. She ignores his protests and Flame blasts a fireball at the Skulkin, forcing them to drop Kai and retreat back into the Underworld. The blast causes boulders to collapse and block off the secret entrance, and when Kruncha and Nuckal later come back, they begin blaming each other for "leaving the stove on."
Battle Between Brothers
Zane compliments Sensei Wu's black kimono. This prompts Sensei Wu to tell him the story of the day Garmadon was cast to the Underworld. Garmadon was trying to steal the golden weapons when Wu walked in. They start a fight, with Wu wielding the Scythe of Quakes and Garmadon wielding the Sword of Fire. Wu swings down the Scythe of Quakes and knocks Garmadon through the wall. The hit the Shuirkens of Ice and sword of Fire together and the ground cracks open, revealing the underworld beneath. Garmadon is able to knock Wu down and he raises up the sword of fire, preparing to finish Wu off. Wu pleads with his brother to stop, but Garmadon doesn't listen. However, before he can finish off Wu, the protection from evil Wu's kimono offered him makes Lightning strike Garmadon and causes him to fall to the underworld. The tale finished, Zane remarks how much more peaceful it is now that Garmadon is gone, only for Jay to fly by wildly on his dragon.