In the wake of a vicious attack upon the palace, the Sons of Garmadon steal the second Oni Mask, and the ninja invite the royal princess, Harumi, into their makeshift family.
While Princess Harumi adjusts to life with the ninja, Lloyd and Jay search for answers about the Oni Masks, while Cole and Zane attempt to infiltrate the Sons of Garmadon.
Zane's near demise at the hands of Mr. E forces the ninja to flee aboard the Bounty, where they discover that a transmission Zane intercepted may reveal the hidden location of the Quiet One.
As Lloyd and Harumi venture deep into Primeval's Eye in search of the third Oni Mask, the ninja attempt to fix the Bounty and make a startling discovery.
The Ninja appeal to the Police Commissioner of Ninjago in an effort to help save Lloyd and thwart Harumi's efforts to resurrect the evil Lord Garmadon.
Just when the Ninja think they have saved the day, Lord Garmadon returns to Ninjago, and frees Harumi, who encourages him to "achieve his True Potential" by conquering the one thing that has always stood in his way - his son, Lloyd.