When the Celestial Clock's countdown finally completes, a mighty beam of energy strikes the Stone Army's camp.
As the energy fades, The Overlord proudly introduces Lord Garmadon to their completed ultimate weapon: the Garmatron, a massive, heavily-armed tank. As Lord Garmadon gazes in awe, a pair of Stone Soldiers arrive with Nya as their prisoner.
Nya says that her friends will find a way to stop Lord Garmadon, but the villain simply stuffs an apple in Nya's mouth and uses her as the "first test subject" for the Dark Matter.
Meanwhile, the heroes return to the beach, where Dr. Julien asks about the horns he just heard.
Master Wu explains the situation: the Celestial Clock has ended its countdown, the final battle is about to begin, Lord Garmadon's ultimate weapon is operational, and Nya is a prisoner of the Stone Army.
Kai assures a worried Jay that Nya will be too tough for the villains to break, and they will see her again. Master Wu turns to Lloyd, who is still dejected over the prospect of fighting his father, and reminds him that it is his destiny as the Chosen One-all of Ninjago depends on his victory.
Misako tells her son that Lord Garmadon is just as reluctant at the prospect of battling his son, and the other Ninja pledge their assistance in the final fight.
"What about Aria?" Lloyd asked
"What do you mean, what about her?" Wu asks
"Yeah Lloyd, she's the Overlord's daughter, she's obviously on their side" Kai says
"Then why was she at the Temple of Light with us?" Lloyd asked
"The prophecy did not mention her at all, so maybe, she can choose her own destiny and maybe see the light" Mesako said
"Thats right, while in the Temple of Light, Aria's place was next to Lloyd in the middle" Cole said
"She was?" Wu asked
"Then.." Mesako trailed off
"Aria is also..." Wu said looking at Mesako
"What?" Cole asked
"It may be possible that Aria has also received the power of the first spinjitzu master" Mesako said
The ninja looked at them shocked, the Overlord's daughter. No way that better not have happened, unless you know...
Well Lloyd leads the charge on Lord Garmadon's base camp, only to find it deserted.
The Falconleads them to massive tracks and a path of destruction leading towards the coast-Master Wu realizes that the ultimate weapon is not meant to attack the Ninja, but to achieve Lord Garmadon's dream of remaking Ninjago in his own image.
Misako is horrified-the resulting influx of evil will upset the balance of the world, allowing the Overlord to return in full-and Lloyd resolves that they can't let Lord Garmadon fire a single shot.
The group moves on, but Zane is forced to say goodbye to his father, who is unable to keep up and decides to head back to the Destiny's Bounty.
As they run, the Ninja reflect on all of their adventures, but the jovial mood is broken when they sense an evil presence nearby.
Suddenly, a crimson Spinjitzu tornado hits Cole and Lloyd, and stops in front of the group to reveal Nya, corrupted by the Dark Matter into a feral slave of Lord Garmadon.
Master Wu realizes that the villains are trying to buy time to fire the ultimate weapon, and he, Misako, and Lloyd carry onward while the Ninja attempt to subdue Nya without hurting her.
The Garmatron finally reaches the coast of the Island of Darkness, where the Overlord tells Lord Garmadon to show Ninjago his power.
At General Kozu's and Aria's command, Stone Soldiers begin loading Dark Matter bullets into the cannon, but Lloyd, Misako, and Master Wu arrive before Lord Garmadon can fire.
To the Overlord's dismay, Lord Garmadon leaves the controls to confront his family-despite their pleas, he insists that the only way they can be together again is if he corrupts the entire world with the same evil that has consumed his being.
With that, Lord Garmadon activates the Garmatron's cannon, only to discover that it has a twenty-second warm-up period.
"You could've told me it had to warm up!" Garmadon shouted
"This idiot" Aria mummbled
"Why would you think a powerful weapon like that could just fire automatically!" Aria shouted at Garmadon
"Well said my daughter" The Overlord said
Meanwhile Misako deflects blasts from the tank's side cannons, allowing Lloyd to jump aboard; however, General Kozu manages to pin the Green Ninja down long enough for the Garmatron to fire.
The warhead soars over the ocean and bursts into clouds of darkness over Ignacia, draining the color from the land and transforming the people into snarling, purple-eyed beasts.
Lloyd attempts to summon his powers as the Stone Army loads another round, but Lord Garmadon activates a trap door that drops Lloyd and General Kozu out of the Garmatron before firing again.
Back in the jungle, the Ninja are having a rough time against Nya, until Zane realizes that they can use their elemental powers on the environment instead of their opponent.
He uses his Elemental Blade to break the chain of Nya's weapon; Jay creates an electric barrier to deflect thrown needles; Cole blinds Nya with a cloud of dust; Kai cuts down a nearby tree so its leaves surround his corrupted sister. Finally, Zane freezes the tree, leaving Nya trapped within a dome.
"this club just became boys only" Jay said
The Overlord begins cackling as the Garmatron's second shot corrupts Jamanakai Village; below, Lloyd laments his failure, but Master Wu assures him that he did his best.
Misako realizes that the balance has been undone, and the Overlord confirms that he is finally free to take over Ninjago.
Lord Garmadon is infuriated at this, raging that Ninjago is his to conquer, but the Overlord reveals that it was never going to be his, shortly before a beam of white light engulfs the top of the Garmatron.
As the Ninja rush up to their allies, Lord Garmadon's hands morph into claws, his limbs lengthen, and the demented laughter of the Overlord issues from his newly-reptilian mouth.
Master Wu tells Lloyd that the creature atop the Garmatron is no longer his father-the Overlord has possessed Lord Garmadon's body.
Misako warns her son that the Overlord will show no mercy, but the Ninja offer their support once again-with determination, Lloyd leads them in attacking the Stone Army.
Seeking more evil power to increase his strength, the Overlord aims the Garmatron's cannon at Ninjago City, but nothing happens.
Looking over the side of his vehicle, the Overlord realizes that the whole of his army is occupied fighting the Ninja, with Master Wu and Misako preventing the Stone Soldiers from bringing the next warhead to the Garmatron.
Although General Kozu attacks Master Wu, the old master kicks him into the Garmatron's loading port-thinking that the next bullet is loaded, the Overlord fires, sending his own general flying into Ninjago City.
General Kozu ends up crashing through the window of the Mojo Dojo, where Dareth sends his students to swarm the four-armed Stone General.
Enraged, the Overlord decides to load the cannon personally, only for Lloyd to leap atop the Garmatron and challenge him to battle.
"Aria load the cannon" The Overlord shouted, Aria nodded and went.
While Kai hijacks one of the Garmatron's turrets to back Jay up against the remnants of the Stone Army, the Overlord knocks Lloyd off of the tank.
Their battle continues on the beach, briefly clashing with energy beams before Lloyd dodges and blasts his foe into the jungle.
The Overlord quickly recovers and flies above the trees, delivering a brutal tackle that sends Lloyd flying. The Overlord gloats that he can keep this up for eternity, but Lloyd is alone-in response, Lloyd removes his mask and asserts that his father will never hurt him.
Lord Garmadon briefly asserts himself from within the Overlord, begging Lloyd to stay strong-the Overlord's confusion and shock gives Lloyd an opportunity to take the offensive.
As they clash with their energy beams once more, Lloyd calls out to his father, whose struggles cause the Overlord to falter.
As Lloyd pushes his power to the limit, the Overlord roars that his father is gone before overcoming Lloyd's attack.
"Aria help me now!" The overlord shouted at his daughter who was nervously watching from the side.
Aria trapped the Green Ninja in a sphere of dark energy and hurled him across the beach. Aria covered her eyes as he made impact with the ground.
Misako and Master Wu rush to Lloyd's side as the Overlord finally turns the Garmatron's cannon on his foes, but the tank's next shot is blocked by the Destiny's Bounty, piloted by Dr. Julien.
Fed up with the interference, the Overlord creates a portal for his army, declaring that they will go to Ninjago City personally to finish the job.
From the back of the Garmatron, Nya mockingly bids farewell to her brother as he leaps at the portal, only to fall short.
Kai screams in fury and despair as the portal closes, leaving the heroes trapped on the Island of Darkness.
Misako manages to awaken Lloyd, who wonders if he has failed the prophecy.
"Thats true you didn't defeat the Overlord, but you didn't lose your life either" they heard a voice say
They looked over to see Aria still standing on the beach looking at where the portal was moments before.
The ninjas realized, she didn't go in. Why didn't she go with her father?
Lloyd stood up and walked over to her picking up a piece of the Destiny's Bounty marked with the symbol for destiny.
Aria put her hands on Lloyd's foot, her hands started glowing green. She was healing Lloyd's foot, she finished and stood up.
Lloyd looked at everyone "You know, Aria's right. Today we didn't loose the battle"
"You just lost the fight" Aria finished, they watched Aria open a portal to ninjago.
"I'll be waiting ninjas, don't be late" she said going through the portal
The portal closed and Lloyd smiled "Thank's Aria"
"Maybe she's not that bad after all" Kai said
Wu looked at the ninjas "Perhaps, she just gave us the confidence we needed to finish the fight, Aria's done what she can for us, now let's hope her father doesn't find out"