Sensei Wu implores the Ninja to start training again to prepare for his brother's return to Ninjago, but ever since Lord Garmadon has escaped, they have done nothing but play video games and waste time. Sensei Wu lectures the four on "not putting off until tomorrow what can be done today," saying that the four have not yet reached their full potential. The Ninja laugh, saying that they'll be ready when Lord Garmadon returns.
Their meeting is interrupted by Nya, bringing word that Lord Garmadon was spotted in Jamanakai Village, sending the Monastery to a state of panic. The Ninja then travel to Jamanakai village to stop Lord Garmadon, only to find the sighting to be his son Lloyd who has escaped Darkley's Boarding School for Bad Boys again.
Lloyd tries to terrorize the village and rob them of their candy, threatening to release the Serpentine on the villagers, but is instead run out of town by the Ninja. Before returning to the Monastery, Kai discovers he has accidentally taken Sensei's bag in the rush, and finds a scroll that tells of the prophecy of the Green Ninja.
None of the Ninja are able to contain their excitement, boasting to the others that himself will become the Green Ninja. All consumed by selfishness, they try to hold a tournament to find who is the best of them all, and thus become the Green Ninja. Unfortunately, the idea backfires when Kai's Sword starts an elemental fire which cannot be put out. Zane attempts to freeze the fire, Jay has a flame on him and Cole hits the fire with his Scythe. Sensei Wu arrives and uses the Shurikens of Ice to stop the fire, before explaining the Ninja must agree to continue their path to unlocking their potential before any of them will become the Green Ninja.
Meanwhile, Lloyd wanders the frozen wastelands of Ninjago, upset his plans have gone awry. Mistakenly, he uncovers an ancient tomb containing a tribe of the real Serpentine known as Hypnobrai. Slithraa attempts to hypnotize Lloyd, but he ducks out of the way and the General is met by his own reflection in an ice stalagmite, accidentally hypnotizing himself in the process. The tribe is now under Lloyd's control, who sends them to steal all the candy in Jamanakai. The Hypnobrai use their power to hypnotize the villagers, bringing more power to Lloyd.
Sensei Wu senses the presence of the Serpentine with his Spirit Smoke and quickly alerts the Ninja, who rush to the village and are able defeat the Hypnobrai, forcing them to retreat. However, Skales, the second-in-command of the tribe, hypnotizes Cole before leaving town, forming a scheme to destroy the Ninja for revenge. After stealing the Hypnobrai Staff, Nya uses the anti-venom inside it to cure the villagers, but Cole remains under Skales's influence.
The game played by the Ninja is actually a scene from The Golden Weapon in the US version. However, in the version aired in Germany, they played LEGO Battles: Ninjago.
The episode name refers to Lloyd unleashing the Hypnobrai, marking the Serpentine's first return to Ninjago since their last defeat. More broadly, it can refer to Lloyd's actions beginning a chain of events that will unleash all of the Serpentine and their "god" upon Ninjago
Errors
When Jay says, "Why would you do that? Why?", Zane's mouth moves despite not saying anything.
When Cole leans back saying "we can train tomorrow," he says it in Kai's voice. Likewise, later on in the episode, Kai has Cole's voice when he's reading the Green Ninja scroll.
