The Corridor of Elders is the 10th and final episode in the fourth season, and the 44th episode overall of Ninjago: Masters of Spinjitzu.
The ninja and fighters discover there's a strategic location called the Corridor of Elders where they can make their last stand against Chen's Anacondrai army...but even with the new Destiny Bounty, their forces still aren't strong enough. Fortunately, Pythor escapes Chen's clutches and discovers there is one spell in the Book of Magic that could stop the war, but at a serious cost.
Chen's Anacondrai army lands in Jamanakai Village as its citizens flee in terror. The army continues onward, as Chen declares they won't stop until every village is conquered.
Meanwhile, the Ninja and the other elemental masters are scattered all around Ninjago, after chasing down the decoy trucks. Nya attempts to contact them from the new Destiny's Bounty, but Chen takes over the airwaves and tells the senseis, Nya, Misako, and his daughter that he wants to make a truce. Garmadon points out that he's the reason the original truce was abandoned, though Wu inquires of his demands: if they, the Ninja and the elemental masters leave Ninjago for good, he won't cause anymore damage. Wu asks for time to think it over, leaving his brother stunned that he's even entertaining the Master, to which he says they need to buy more time. Chen advises Garmadon that he should listen to Wu due to his way with words and ultimately reveals to Misako that it was Wu who wrote the letter that caused her to fall in love with Garmadon. Chen then reveals he lied about the truce and only wanted to reveal the truth. Angered, Wu declares that Garmadon is no sensei, though Skylor quickly breaks up the fight telling Wu that since Chen divided the Ninja, he's now trying to divide the brothers.
In Chen's camp, Pythor is still running from the rodent, though, he manages to escape and comes across the book of spells. Just then, Cyrus Borg delivers a message via the radio that more villages have been overrun. Pythor states a true Anacondrai wouldn't stand for it, which helps him decide to find a solution.
Elsewhere, Lloyd meets up with Neuro who informs the Green Ninja that Chen's army is heading west. Lloyd instructs the Master of the Mind to send a message to the other elemental masters ordering them to Nya's Samurai X Cave. Once everyone has returned, Kai remarks to Skylor that the spell is wearing off faster, though she points out that Chen is still hurting everyone. Lloyd notices his uncle acting cold towards his father and realizes the truth behind the letter has been revealed. Nya informs them that Chen has taken over the entire eastern coast in the time it took for them to get back. Gravis questions how they can stop them since almost all of them have lost their dragons, to which Wu points out that the Corridor of Elderswill be the best place to make their final stand, and the elemental masters agree. The Ninja journey all over Ninjago to rally support from the citizens.
The Ninja, their allies, the Elemental Masters and the citizens of ninjago.along with the Serpentine, the Nindroids, The Stone Army the Skulkin the pirates and the inmates from Kryptarium Prison get to the Corridor and prepare to start the ultimate battle against the Anacondrai Cultists. The group manage to keep the snakes from passing and do what they can to make sure they keep the upper hand. As Shadow takes control of a bladecopter, Nya, Misako and the sensei's use the Destiny's Bounty to destroy the vehicles, managing to save Skales who expresses relief at seeing the ship again. Having had enough, Chen uses the Roto Jet to widen the opening allowing his followers to pass through the Corridor.
Pythor, having escaped Chen's camp riding the rat and carrying Chen's spell book, rides up and tells Lloyd to take him to his father because he knows the way to end the battle. As Lloyd does so, Skylor attacks Chen as revenge forwhat he's caused. Lloyd carries Pythor to the Destiny's Bounty where he tells Garmadon that he can stop the Cultists by sacrificing himself and going to the Cursed Realm in the place of Arcturus and the other Anacondrai generals, so their spirits would be unleashed on the cultists. Everyone is reluctant, but knows it must be done, except Lloyd who gets angry that his father could desert him again and not come back this time and flies away on a flyer. As he dives back into the battle, he remembers his past with his father while defeating the Anacondrai. Wu begins to read the spell to open the portal to the Cursed Realm, while Misako tells Garmadon she's already forgiven him about the letter. Lloyd then returns to the Bounty, saying that he will do send him off instead, since it only seems fair that he does it. The portal opens, and Garmadon violently ascends into it, unleashing the spirits of Arcturus and his troops who quickly curse the cultists and turn them into ghosts. Chen tries to reason with them, but Arcturus calls him a liar, a cheat and an imposter before he curses him. As a last resort, Chen tries to get Skylor (who is now completely back to normal) to help him, though she just watches him receive his punishment, gets sent into the portal, which then explodes. The war ends, but Lloyd is sad because of his father's apparent death. Arcturus's spirit comes to Pythor and says that he made their ancestors' proud, and turns him into back to normal size. Arcturus then thanks Lloyd for his and the others' help for doing what they couldn't: uniting all kinds as one. He then says that Lloyd and his friends are now Ninjago's greatest warriors before flying away.
Later that day, the Ninja and the Elemental masters agree to keep in contact and come to their aid should they need it. As Skylor begins to leave, Kai awkwardly but successfully offers her the chance to become a Ninja: though flattered, she declines as since Chen is gone, she is now owner of the noodle house. Just before the two are about to kiss, Dareth interupts the moment where Skylor immediately says she'll put puffy potstickers back on the Noodle House's menu. Dareth is satisfied, while Kai and Skylor agree to keep in touch before the orange ninja leaves.
Karlof gets everyone to clean up the Corridor of Elders while the ninja, Nya, Wu, and Misako sit around a fire on a broken statue, watching construction workers building statue of Garmadon in the Corridor. Lloyd tells that today they will say goodbye to a legend and burns the book in the fire. In the end, a green ghostly figure appears spinning in the air (probably doing Airjitzu) and screams "Morro!" indicating the spirits of the Anacondrai weren't the only ghosts that were released from the Cursed Realm.