The episode starts with Zane breaking his previous record for holding his breath underwater, astonishing his comrades. After he surfaces, the Ninja discuss their many accomplishments and wonder if they have reached their full potential. They seek out Master Wu, who tells them that they have only reached their physical peak; their true potential requires mental enlightenment as well.
Master Wu begins to relate a story about his childhood, talking about how he and his brother were best of friends. One day while they were practicing their skills, Wu lost his katana, and his older brother sought to find it, knowing their father would not be pleased. Garmadon found the katana after clambering over the wall, however, he is bitten by a small green snake. In the following days, Garmadon developed an increasingly darker nature, which Master Wu attributes to the snake bite, as it came from "a legendary snake"—the Great Devourer.
The tale told, Master Wu declares that he is going on a journey, alone. The Ninja are taken aback, but they and Nya oblige, dropping Wu off at a nearby mountain. Afterwards, the Ninja decide to go to Jamanakai Village to post signs about the missing Fangblades. As Zane is posting signs, he sees the Falcon. A montage shows the Ninja traversing different terrain to reach the Falcon's destination. During the montage, Jay, Cole and Kai become too tired to go on while Zane proceeds into a frosted forest. As he follows it, the Falcon suddenly drops to the snowy ground.
Zane picks it up and finds it is mechanical. Zane is then disturbed by a robot, though quickly destroys it to find the same symbol on the robot and the Falcon. Zane proceeds into a hollow tree which he discovers is a workshop. While searching through the building, he finds a blueprint with a figure on it and drops to his knees, yelling in disbelief.
Meanwhile, Master Wu enters a tea shop and requests Traveler's Tea. Mistaké, the owner, claims not to have heard of it but upon receiving payment brings out a pot, warning Master Wu that those who drink the tea do not return. Saying that he will not bother her again, he leaves the shop.
Back at the forest, the Ninja find Zane, still on his knees. They question why he is distressed when Zane reveals to them by opening up his torso that he is a robot. The Ninja assure him that although he might not be human he is still their brother, but Zane asks to be left alone after the revelation.
Kai, Jay, and Cole leave the workshop at Zane's request but are soon attacked by Treehorns. They dodge their attacks at first, but are unable to defeat them and are quickly subdued.
In the workshop, Zane takes another look at his blueprints and, realizing he has a Memory switch, flips the switch on. He remembers his father, Dr. Julien, and the different things he taught him over the years. His father explains to Zane that he was built to protect others, and wishing to save his son the pain of heartbreak, turns off his Memory switch before passing away of old age.
Zane, having regained his memories, sheds a tear for his father before rushing out to help his friends. Together they defeat the Treehorns, but things take a turn for the worse when the Queen arrives. Realizing now who he is, Zane overcomes the obstacles of his heart and reaches his True Potential. Using his newfound powers, Zane freezes the Queen as the other Treehorns retreat. While the other Ninja are happy for Zane for being the first to unlock his True Potential, Zane proclaims with confidence that they are going to find Pythor.
Meanwhile, Pythor is still desperately trying to unite the snake tribes. He has been attempting to solve a riddle: "When the five fangs unite as one, the path toward the Devourer has begun." The other leaders begin to doubt Pythor, saying that snakes will begin to ask questions. Just then, Acidicus and Skalidor get into a tussle with one another, and their staffs are tossed aside. The venom from the staffs drips onto the floor, giving Pythor an idea. He gathers all of the staffs and puts them in a leaning formation over the table, sliding a scrap of paper underneath. The venom from the five Snake Staffs drips onto the paper, creating a map showing the locations of the four Fangblades. Having solved the riddle, Pythor and the others rejoice.
On a tall mountain, Master Wu is shown to be meditating before pouring the Traveler's Tea in a circle around his campfire. A vortex then erupts, and he steps into it. He reappears in another dimension, where he is greeted by his brother, Lord Garmadon, who then proceeds to laugh ominously.
The episode's title refers to Zane (and, to a lesser extent, the Falcon), who is revealed to be a mechanical being. This twist is foreshadowed by the opening scene, showing a mass of clockwork before zooming out to show a pocket watch, as well as Kai's comment about Zane being "inhuman."
The episode title may also refer to the Serpentine's search for the Four Silver Fangblades, which will become a race against time as the Ninja try to stop them from unleashing the Great Devourer.
This episode features the first appearance of Dr. Julien (in a flashback) and Lord Garmadon's new, four-armed form. It also marks the only appearances of the Juggernaut and Treehorns in the series.
The title sequence is updated in this episode, featuring the Ninja in their ZX outfits.
Errors
When the Ninja visit Jamanakai Village and Cole asks Kai if everything's all right, he speaks with Jay's voice.