Aboard the Destiny's Bounty, Lloyd Garmadon is discussing with the Ninja how he would attack a Serpentine.
"First, I'll stomp on his tail. Then when he turns, a thunder clap to his ears. Then when he's stunned, I'll disarm him" Lloyd said
Cole shook his head "Too late, he's already hypnotized you and now you're under his control"
"Or he's already put you in a squeeze" Zane added
"Or spit on you with his hallucinatory venom. Trust me, bad stuff" Kai said
Lloyd groans "Uncle, what's the best way to stun a Serpentine if you don't know what kind they are?"
Wu was entering the room with a box "Hmm... sadly, it was the Sacred Flute you four carelessly lost"
"Hey, no, no, no, we didn't lose it. Pythor stole it" Jay corrected
W sighed "Whatever the case, without it I fear we have nothing to combat their powers. We may have prevented them from uniting in the past, but they will try again, and one day they will be stronger"
"Don't worry. I've almost reached my Full Potential, and when I become the Green Ninja, we're not gonna need any magic flute" Cole said
Kai scoffed "You're gonna be the Green Ninja? Hahaha, don't make me laugh, you can be the Purple Ninja"
Zane intervened "I thought it was decided that I was destined to become the Green or Purple Ninja"
"Oh! The only thing decided about you, Zane, is that you're weird" Jay said and the Ninja start arguing.
Lloyd rolled his eyes "Yeah, yeah, yeah. What's in the box?"
"Your new uniforms" Wu replied he Ninja gasps in awe
The 4 ninja changed into them
"Whoa! They've got, like, armor." Jay said excitedly
Kai smiled "I love the gold highlights"
"Battle claws!" Cole shouted amazed
"The material is really light and breathable" Zane said
"do I get anything?" Lloyd asked
"you get..." Wu handed him the box "the box"
The alarm went off.
Cole looking at the monitor in the bridge "A small faction of our slithering friends are stirring up trouble at Mega Monster Amusement Park"
Lloyd turned happy "Amusement park? Can I go? Can I go with you, please? Let me make things up. I can help."
"I'm sorry, nephew. You will stay here, where it's safe" Wu said
"Oh, Ninja get all the fun" Lloyd whined
The ninja jump off the Bounty and use their vehicles to land, posing to show off their new uniforms. Upon arriving, however, the Ninja find that the Serpentine threat has been taken care of. Nya then comes over to them "someone called Samurai X already arrived and handled them"
"their is another hero?" Zane questions
"seems that way" Cole said annoyed
Master Wu then comes out of a gift shop with cotton candy "this Samurai may help you five better yourselves through some healthy competition- oh ferris wheel!" with that he ran off
"yeah, that's a great idea" Cole said
"whoever catches the Samurai first is the Green Ninja" Kai said and the other 3 boys agreed
Then the Ninja set off to find the mysterious warrior. Kai, who is patrolling Ninjago City, drops Lloyd off at the Kiddie Arcade.
"Hey I want to come too" Lloyd whined
"Sorry kiddo but I gotta prove im the green ninja once and for all" Kai said
After Kai speeds off, Lloyd overhears the Serpentine preparing to head to the Lost City of Ouroboros. Lloyd dons a Serpentine disguise, and follows the snakes on to a bus to the city.
After a long drive, they reach the city, which is resting in the Sea of Sand. They all pile into a colosseum, where Pythor is announcing a Slither Pit. He tells the Serpentine that if he beats all of the Generals at once, he wants their complete, undivided loyalty.
Aria gives Pythor the stolen Sacred Flute to use against the Generals during the fighty. Once Pythor emerges from the Slither Pit as the victor, he demands for the Serpentine to bow to him. When Lloyd attempts to bow as well, however, he accidentally drops a part of his disguise, revealing himself to the tribes.
Later at the Destiny's Bounty the ninja meet up. The boys are complaining about their failed attempts to try and capture the Samurai.
"where is Lloyd" Wu asked looking around as he came in
"I don't know, Cole was supposed to pick him up" Kai claimed
"not me, Jay was" Cole argued
"no" Jay said
"I am afraid of what might have become of my nephew, Ninja go find him, all of you" Wu commands
"yes master" They all said and headed out
They head over to the Arcade Kai had dropped Lloyd off at, and watch security camera footage from outside the building, spotting Lloyd putting on a Serpentine costume. Upon discovering his footprints outside, the Ninja use their vehicles and begin to track down Lloyd. They come upon the gates of The Lost City of Ouroboros, and slip past the guards.
They come upon the border of the colosseum and spot Lloyd in a cage beside Pythor, but when they rush in to save him, they trigger a trap and are locked inside a cage as well, dropping their Golden Weapons. The Ninja are led to the center of the colosseum, and Pythor announces another Slither Pit.
"Ninja vs Samurai, let's see who's better" Pythor says slyly
Just then, Samurai X is also led out. The duel begins and the Samurai throws projectile weapons at them, but they dodge most of them. Pythor makes the game more interesting by tilting the stage and revealing spikes. As the Ninja hang onto Samurai X's exo-suit, he tells them to keep the charade up, and begins flying. However, the suit is too heavy and he ejects himself from the mech, allowing the Ninja to escape safely, much to their anger.
As the exo-suit falls to the desert ground, Zane, Jay, and Cole fall as well, with the exception of Kai, who fell in a different direction. Kai spots Samurai X without his mask, revealing himself to be Nya. Nya explains to Kai that she was tired of how much focus was being placed on the Ninja and she wanted to help out in her own way. Kai promises he won't tell the others, and Nya hands Kai the Golden Weapons she secured.
Back at the Destiny's Bounty, Kai explains to his teammates that Samurai X just handed him the Golden Weapons and left. As Master Wu leaves the Ninja to go to bed, he hands Nya one of the Samurai's weapons, telling her knowingly that "iron sharpens iron, and sibling sharpens sibling," expanding upon what he had told the Ninja earlier on.