Long before time had a name, the First Spinjitzu Master created Ninjago using four elemental weapons. But when he passed a dark presence sought out to collect them all; Lord Garmadon. So I, Sensei Wu; his brother, sought out to find four ninja to collect them first...
Immediately continuing the story from where the first season left off, 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 lectures the four on "not putting off onto 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 Garmadon was spotted in Jamonicai village, sending the Monastery to a state of panic. The out-of-shape Ninja then travel to Jamonicai village to stop Lord Garmadon, only to find the sighting to be false and the fake Garmadon to be just his son who has escaped his boarding school for bad boys, Lloyd Garmadon.
Lloyd tries to terrorize the village to rob them of their candy, and threatens to release the "Serpentine" on the villagers, but instead is 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 Ninjago; one ninja will rise above the others and become the Green Ninja destinated. None of them are able to contain excitement, boasting to the others that himself will become the green ninja.
eanwhile, 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. The Hypnobrai general attempts to hypnotize Lloyd, but his short size causes the general to seeing himself in a reflection, and letting Lloyd take control of him. The tribe is now under Lloyd's control, who sends them to steal all the candy in Jamonicai. The Hypnobrai use their power to hypnotize the villagers, bringing more power to Lloyd. 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.
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. Sensei senses the presence of the Serpentine 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 for the tribe, hypnotizes Cole before leaving town, forming a scheme to destroy the ninja for revenge. After stealing the Snake Staff, Nya uses the anti-venom inside it to cure the villagers, but Cole remains under Skale'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 are playing LEGO Battles: Ninjago. Additionally, in other versions, Zane is found eating the sandwich in the fridge instead of simply leaving a note behind.
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.
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.
Sensei Wu kicks Cole's pizza out the doorway, however, it disappears soon afterwards.