Extended: The Mechanic and his henchmen infiltrate an old electronics warehouse in search of a mysterious motherboard. The ninja learn of the heist and arrive to thwart the attack. But they're completely in the dark as to what the Mechanic wants with it, so they head to the Mechanic's headquarters looking for clues. There, the ninja find the legendary, unreleased arcade game called Prime Empire. Realizing the game is missing a motherboard, Jay inserts the motherboard and the game boots up. While Jay plays the game, the other ninja make their way into the Mechanic's private office where they intercept a phone call intended for the Mechanic. It's a mysterious new villain called Unagami, for whom the Mechanic seems to be working. Meanwhile, Jay accidentally triggers an energy pulse that converts all of the arcade games in Ninjago City into Prime Empire arcade games.
He and his henchmen investigate the hardware in the warehouse, but as soon as he sees it, he claims a motherboard with a V-shaped signature inscribed on it. The Mechanic's affairs are interrupted by the ninja, who jump towards them from above. They fight, but The Mechanic is able to flee with the motherboard. The ninja follow behind.
Cole drives his Rock Cycle, and Kai drives Lloyd, Jay, Nya, and Zane on his ATV. They pursue The Mechanic on the streets, but he pushes the Katana 4x4 onto a building, which causes it to lose control and stay behind. Cole remains on The Mechanic's tail, sticking a cable to his truck and tying it to a pole, which ultimately causes the truck to malfunction. As soon as The Mechanic gets out of his Noodle Truck, the ninja surround him. Jay takes the motherboard from The Mechanic but is confused by the design.
The Police Commissioner sends The Mechanic away, and thanks to the ninja for their help. Jay continues to examine the motherboard. He tries to give it to the Police Commissioner but gets interrupted as soon as the police are informed of another emergency and leave. The ninja decide to go examine The Mechanic's headquarters after realizing that the Mechanic tried to escape there.
Jay opens the door, peeking to be sure there was no danger. The Mechanic's former arm falls on Lloyd, who is frightened. As soon as Jay sees an arcade cabinet, he tells the ninja all about Prime Empire, though they do not feel as excited. Jay plugs the Arcade Pod to an outlet to show them the game, but it still does not work. Instead of watching Jay make the Arcade Pod turn on, they decide to leave him and go investigate the rest of The Mechanic's headquarters.
Walking through a hallway, Cole is captivated by The Mechanic's hats.
Meanwhile, Jay complains that he cannot get the Arcade Pod to turn on. Checking the back of the Arcade Pod, he sees a disc receiver, so he grabs the motherboard he took from The Mechanic and inserts it. The Arcade Pod turns on with a red light and in a couple of seconds releases a shockwave of red energy and knocks Jay out. The ninja are surprised by what it was. It passes by The Mechanic in handcuffs entering the Police Station, who cackles. As the surge of energy passes by an arcade, all the video games get replaced with Prime Empire. A player puts his hands together, preparing himself to play the game. Jay wakes up to see Prime Empire booted up on the Arcade Pod, so he approaches the game to play.
Kai sees notes with the same logo on the motherboard on The Mechanic's bulletin board, and Lloyd finds a notebook that also has the logo. A monitor boots up behind some books, so Zane pushes them aside to see it. the monitor questions the ninja if they found the motherboard, and Zane responds typing in the keyboard. The monitor replies back, saying that Unagami is pleased and to activate the game, then turns itself off. Lloyd questions who Unagami is.
Jay continues grinding Prime Empire happily. He is greeted with a message saying he reached Level 13 in the game. The Arcade Pod asks if he would like to enter Prime Empire. Jay responds yes and presses a red button. The Arcade Pod opens like a door, revealing a white light behind what were the screen and buttons. Jay is attracted to the light and disappears into the Arcade Pod, which then closes and shuts off. The ninja return to see Jay, but he was already gone.
Meanwhile, Prime Empire begins to boot up on more and more Arcade Pods around Ninjago City.