Secrets of Forbidden Spinjitzu: Aspheera

Having grown complacent in the wake of their victory over the Oni, the ninjas are enjoying life, playing video games, sleeping in, and soaking in a hot tub (fashioned from one of the monastery's enormous bells). Unfortunately, this behavior quickly grows tiresome and the ninja are confronted by Master Wu, who accuses them of not taking their duties seriously. The ninjas deny this, and Wu decides to put them to the test with a series of booby traps and pranks intended to test their reflexes and skills. Among the more dangerous challenges, the ninja must catch a dangerous breed of chicken that grows wild in the hills surrounding the monastery. Put to shame by the chicken, the ninjas ultimately realize: Wu is right. They have gone soft. They decide to take on a new quest to get back in shape.

Realizing they have gone soft, the Ninjas search for a quest to reignite their Spinjitzu training and try to cooperate with the police in fighting crime; unfortunately, Ninjago City is enjoying a period of rare tranquility. Having given up hope, the Ninjas learn of Clutch Powers' recent discovery and decide to go exploring with him.

The Ninjas set off for their quest in the Desert of Doom, but on the way are attacked by an ancient giant scarab beetle. Eventually, they manage to escape it but are stranded in the middle of the desert.

To repair the Land Bounty, the Ninjas must retrieve a critical engine component that has been swallowed by the giant beetle. Zane decides to get swallowed himself, and once he has found the component, the Ninjas pull him back up with a rope. Then, they fix the Land-Bounty and escape the beetle.

The Ninjas persuade Clutch Powers to enter the Ancient Pyramid with them and they survive many booby traps along the way. However, they accidentally release Aspheera from her tomb, steal Kai's powers, bring the Pyro Vipers to life, and entomb the Ninjas. She then leads her forces toward Ninjago City, looking for a "treacherous deceiver".

Nelson, the honorary ninja from Skybound who broke his leg, teams up with Antonia on his first day as a paperboy. While trying to deliver the papers around a rampaged by the Pyro Vipers Ninjago City, they get a message that the Ninja is in trouble. Nelson persuades Antonia to help him warn Master Wu.

The Ninjas are trapped in the pyramid and try to escape but encounter encroaching lava and traps along the way. They soon understand that their lack of coordination as a team may prove deadly and work together to escape the pyramid. However, when things get very difficult, the Ninjas are saved by Pixal, who tells them of the Pyro Vipers' attack in Ninjago City.

While the Pyro Vipers attack Ninjago City, reporters newscast the event which has become known as Snaketastrophy. Meanwhile, Aspheera learns of the Scroll of Forbidden Spinjitzu and sets off for the Ninjago Museum of History, while the Ninjas reach the city and battle the Pyro Vipers.

The Ninjas rush to the museum to recover the scroll before it falls into the hands of Aspheera, but they arrive at the same time and battle for the scroll. Its power surpasses Lloyd, but Aspheera acquires the scroll and traps the Ninja. A fan named Jake prompts Kai to never give up and save his friends.

While Aspheera pursues revenge on the "Treacherous Deceiver" who betrayed her, the Ninjas go underground seeking the Serpentine. There, they make a discovery leading them to believe Lord Garmadon is the "Treacherous Deceiver", but Wu corrects them revealing himself to be the one.

Wu tells the ninjas a story about him and Garmadon crossing Serpentine Territory, getting arrested, teaching Aspheera Spinjitzu, and attacking Aspheera because she used Spinjitzu for evil.

Having learned Master Wu is the "Treacherous Deceiver", the Ninjas find themselves under siege at the Monastery, trying to protect Wu from Aspheera. The Pyro Vipers manage to enter the Monastery, but the Ninjas, Pixal, and Wu have hidden in the underground base.

The other Ninjas learn of the second Scroll of Forbidden Spinjitzu's location from Clutch Powers and break into the Explorer's Club to obtain it, running afoul of the club's manager and irritating club members. In the end, they obtain the scroll but wreak havoc in the club.

Aspheera breaks into the underground base and confronts Wu, but the Ninjas arrive with the second scroll and battle her. Zane eventually defeats her, but she manages to strike him with her scroll. Although the Ninjas believe Zane's dead, Wu discovers from Aspheera, who has been imprisoned, that Zane is banished to a distant and remote realm called the Never-Realm.

Having learned Zane is not dead from Aspheera, but has been banished to the Never Realm, Master Wu prepares to go after him, but the Ninjas want to come along as well. When he denies it, they take matters into their own hands and defy him. However, Wu uses the Scroll of Forbidden Spinjitzu to stop the Ninja from leaving. However, the Ninjas defeat him and go to the Never-Realm, before Wu warns them that there is no way back - the reason it is called the Never Realm.