Lloyd stands on the deck of the Destiny's Bounty as Y/n goes to his side to hug his waist as he looks down at the kids who were playing soccer in Jamanakai village.
"Lloyd? Lloyd! Concentrate!" Kai tells the boy.
"Now that the Bounty is in our possession again, we can train you more effectively. But you'll have to focus. One more time." Zane says.
"Oh, but we've been training all day."
"It's all to get you ready to face your father. Now, in position. Y/n's already finished," Cole says.
Lloyd sighs before the ninjas put on their ninja hood on and Lloyd yawns before the ninjas get ready to attack. "Whatever."
Kai charges, but Lloyd punches him. He yawns and Jay and Zane charges at him from the air.
"Ninja, go!" Lloyd calls before doing Spinjitzu, knocking both ninjas down.
Cole then goes behind Lloyd and slide kicks him. Lloyd gets knocked into the air before Y/n catches him in her arms.
"You know, I always thought the guys caught the girl," She jokes before Lloyd blushes and gets out of her arms.
"That was fun. Are we done?" Lloyd asks.
"Oh, come on. You're better than this. What's on your mind?"
"Well... The latest issue of Starfarer just came in at Doomsday Comix and it's a limited run, so if I don't go out and get it, it's going to sell out. Last they left off, intergalactic rogue Fritz Donogan was surrounded by the imperial sludge. And if I don't find out if he gets out alright, I think I might have my own doomsday."
"The fate of Ninjago rests on your shoulders, along with Y/n's. As the Green Ninja, you have a giant responsibility to hold. I'm sorry, but you don't have time for such childish things," Kai says.
"Other kids get to play and have fun. All we ever do is train," Lloyd complains.
"Guys, there's been a break-in at the Ninjago City Museum of History and the security cameras picked up you-know-who," Nya says.
"Garmadon!"
"Voldemort!" Y/n replies.
"We have to stop him before he uses the Mega Weapon to start another one of the diabolical plots."
Lloyd goes to them. The ninjas look at him as he sighs.
"Yeah, yeah, yeah. I can't go and it's safer if I stay here and train."
The ninjas nod as Lloyd sighs, folding his arms disappointment.
"We'll meet up at the Bounty as soon as we're done," Kai says.
"We'll be waiting for your safe return."
"Come back in one piece, big bro. And try not to get hurt," Y/n says before her big brother chuckles.
"Pinky promise," He says before they speed off.
Lloyd sighs. "Too old for comic books and too young to fight. When are they going to make up their minds?"
"Come on, pint size. Show me what you got," Nya says before Lloyd yawns and walks away.
Later that night, at the museum, the Serpentine enter the area. Skales then points his flashlight at the painting of a Serpentine.
"Boy, did they get that wrong!" He snickers before they resume walking around.
"Why would we come to a museum if we weren't going to steal anything from it?" Acidicus asks.
"Because Master Garmadon...has another plan to destroy the Ninja," Fangtom says.
"'Master Garmadon?'" Skales sneers. "Ha! He's no master of mine since his so-called Mega Weapon has failed every time. I don't see why we don't call our own shots."
"Because this time I will not fail," Garmadon says as Skales drops his flashlight from the fright.
"Yes, Lord Garmadon," Acidicus, Fangtom and Skalidor says as they bow down.
"Yes, Lord Garmadon," Skales says before reluctantly bowing down and they rise soon after.
"Behold, Dromaeosaurid Theropod Grundalicus, otherwise known as the Grundal. Although now extinct, in its time, it was the most fear and dangerous creature in all of Ninjago, with claws that could slice through steel, heightened senses that could detect its prey from miles away. It could track the stealthiest of Ninja, and once it had picked up your scent, there was no hiding from it."
"The Grundal? I heard about them. Boy, am I glad we live in an age where we don't have to deal with those things," Jay chuckles.
"Thanks for the history lesson, but what are we going to do with a pile of bones?" Skales asks.
"I am going to make it so the beast shall walk again."
"Yeah, right. Well, show us then," Skales challenges.
Garmadon turns to the skeleton as he raised his weapon. "Rise, Grundal, and feel the strength of the Mega Weapon! I wish to create the power to make you young. Turn back the clock so that you are no longer extinct..." He says as the weapon glowed. "But hungry, hungry for the Ninja."
"Oh, no. He's bringing it back?" Jay asks.
"Not if we have any say in the matter."
While Garmadon was still trying to bring the Grundal to life, the ninjas came out of their hiding spot with their weapons raised.
"The Ninja. Stop them!" Garmadon commands.
The ninjas move along the top floor as the Serpentine throw their weapons at them, missing.
"Rise, Grundal. Rise!"
"We can't let him finish. Go!" Cole says.
The ninjas then jump on the skeleton.
"Stop them!"
"This is not a solid plan, Cole," Zane says before all of them, but Kai, fall to the floor.
"I feel pretty alone up here."
The others look as Garmadon keeps bringing the Grundal to life. While he was falling, Kai threw his sword at Garmadon, hitting the Mega-Weapon out of his hands. Kai then lands on Zane and Jay.
"Not again. Not again!"
"And you said it wouldn't fail."
"Retreat!" Garmadon said before he took his Mega-Weapon.
Jay laughs. "We stopped them. It didn't work."
"Curse you, Ninjas!" Garmadon said before running away with the Serpentine.
Jay laughs. "Well, I thought we handled that well," He said as he sees the Serpentine Generals try to steal a sarcophagus. "Hey, they're trying to steal the golden sarcophagus."
The Generals run as fast as they could through the back door as the ninjas follow.
"After them!"
"That's our way out of here," Skales says as they see a sewer hole.
Skalidor opens the sewer hole cover before they try to get their loot in. "It won't fit."
"Forget it. Let's get out of here."
The ninjas continue running to them before Skales closes the sewer hole cover.
"I can't believe we couldn't catch up to them. I'm usually faster than that. It's as if my legs were half the size," Jay says, his voice oddly high pitched.
"I don't remember that thing being so big. Did it grow?" Kai asks, also high pitched.
"Or did we shrink?" Zane asks.
His voice was high pitched as well.
"Uh, guys," Kai says as he points at a glass door that showed that they had become kids.
"We've shrunk!" Jay yelled as he and the others removed their hoods.
"We're... we're kids!" Kai says.
They scream, terrified.
"Oh, this is bad. This is so bad on so many levels!" Jay yells.
"Oh, it's impossible! We must be dreaming, Zane. Tell me we're dreaming!" Cole yells.
"Nindroids don't dream. Perhaps Garmadon succeeded in turning back the clock, but instead of reviving the Grundal, it only affected us."
"Yeah, but Nindroids don't turn into kids. Explain that, genius," Jay says.
"I've extended my logic parameters, but nothing is coming up. This does not compute," Zane says as his right eye twitches and sparks fly out.
"Okay, fine. I get it. We're all in this together," Cole says as he walks to the sarcophagus. "Oh, but I can't be a kid again, I hated being a kid. You can't drive, nobody listens to you. Oh no, bedtimes!" He says as his teammates walk up to him.
"I told Nya we'd meet back at the Bounty. I'm sure Sensei will know what to do," Jay reassures.
They then hear sirens as a police car pull up in front of the kid ninjas.
"Well, well, what do we got here? Looks like we've caught our culprits to the museum heist. Who would have thought it was just a bunch of brats? What have you got on, Apple Dumpling Gang? Pyjamas?" The police officer and his partner laughs.
"These aren't pyjamas! We're Ninja," Jay insists.
"Yeah, yeah, and I'm Santa Claus," The police officer replies.
"Ninjago!" Kai says before he spinjitzus and lands on his friends. "Whoa! Our Spinjitzu doesn't work. We're too small."
"Easy, kiddo," The police officer says as he grabs onto Cole. "You're coming with us to the precinct," He adds as he holds onto Kai.
"Look," Kai chuckles. "Officers, this has been a grave misunderstanding. My friends here and I are simply trying to help out."
"Hey, you can tell all the stories you want when we return to the museum tomorrow to explain why you stole this."
"But we didn't steal it."
"Zip it!" The officer said before he tosses the ninjas to the back of the police car.
"You have the right to remain silent."
His partner laughs. "Kids."
The following morning, the ninjas weren't back from their mission.
"Their mission shouldn't have taken more time than it has," Y/n says.
"Oh, they should be back by now," Nya agrees.
"Oh, I fear something horrible has happened to them," Wu says.
Wu turns to his nephew, who quickly changes his comic to the lesson book. "Lloyd, you're in charge of the Bounty while Nya and I have a look around town."
"Uh, yeah. Sure thing," Lloyd says before Wu and Nya walk away. "Okay, Fritz Donogan, looks like it's just going to be you, me, Y/n, and the imperial sludge."
"We're sorry for stealing," Kai, Jay, and Cole say to the museum's curator.
"But we didn't. I don't understand," Zane says.
Kai shushes him. "The quicker we get out of here, the faster we can figure out how to return our bodies back to normal."
Zane kneels down. "I'm sorry for stealing, too."
"Thank you, little boys, for returning the sarcophagus. You did the right thing. But, what about the bones?" The Curator asks.
Jay stands up, confused. "Uh, what bones? We didn't steal any bones."
"The Grundal bones," He says as he gestures to the empty exhibit.
"The Grundal bones?" Jay asks as the other three stand up. "They're gone! You don't think—"
"It just walked out of here," Kai says.
"Theoretically, it is possible that if Garmadon successfully reversed the years on us, he reversed the years on the Grundal and brought it back to life," Zane says as they gasp.
"You guys have to believe us. The Grundal's been brought back to life, and it's on the loose. It's sole existence is to hunt Ninja and as long as we're here, everyone's at risk," Jay tells the police and curator as they laugh.
The officers then put them on a bench.
"Well, we'll keep a good lookout for anything that goes bump in the night, okay? Now, you four sit still until we call your parents to come pick you up."
The officers laugh before leaving the ninjas alone.
"We've gotta get out of here. Like, now," Cole says.
Jay then notices a group of children who were being chaffered by a teacher. They were at the museum for a school trip.
"Follow my lead, boys," Kai says as they leave the bench.
The ninjas then swipe different things from the other students. They disguised themselves with normal children's clothes.
"Oh, this is so humiliating," Jay says as he put on a blue shirt with a butterfly and a hat he stole.
"I'm afraid if we can't use our Spinjitzu, we'll be no match for the Grundal," Zane said, wearing a blue and white shirt with the number '13,' on it.
"Then we have to get back to the Bounty," Kai says.
When the group stepped out of the museum, the ninjas ran past the teacher.
"Huh? Where are you going? Come back," The teacher says before they hear a big footstep. "What was that?" He asks as he looks up to the roof. "Hello? Is anyone here?" He asks again before the Grundal reveals itself. "A monster!" He screams as everyone runs away.
"Collect call, please," Jay says as Cole and Kai hold him up. "Hold me steady," He says as Zane acts as a lookout.
On the Bounty, Lloyd is playing a game as Y/n watches. Lloyd and Y/n then get distracted by the sound of the telephone ringing. Y/n picks up.
"Destiny's Bounty," Y/n greets.
"Y/n, Lloyd!" Jay says. "It's Jay! Let me talk to Sensei!"
"Jay?" Lloyd asks.
"Where are you? Why haven't you returned? Sensei and Nya's out looking for you," Y/n says.
Jay groans. "Apparently, you need parental permission to take the bus and we can't seem to get out of the city!"
"Uh, what?" Lloyd asks.
"Oh, never mind, it's a bit complicated. Just meet us at Buddy's Pizza in ten minutes. And bring our weapons."
"Weapons?" Lloyd asks before he falls off his seat and Y/n giggles.
"We're on our way."
Lloyd and Y/n enter the meeting venue.
"Really? Of all places we could meet, you pick this place?"
"What? I like their pizza."
"Psst, Lloyd. Y/n," Someone whispers as they turn to the person.
"Beat it, brat. I'm on a mission," Lloyd says.
"It's me, Kai."
The two children look closer to realize that these were the kid version of the ninjas, and Lloyd drops the weapons. "Whoa! What happened? You're, uh, uh, small!"
Everyone in the restaurant then turns to look at them.
"Keep it down. We're trying to lay low," Kai says. "Your father's Mega Weapon not only to turned us into kids, but unleashed a creature whose sole purpose is to hunt down Ninja."
"Typical Garmadon," Cole says.
"And now, every time we try to tell someone," Jay says as Lloyd and Y/n pick up the dropped weapons. "They won't believe us, 'cause we're kids."
Y/n and Lloyd look at each other before laughing.
"What's so funny?" Lloyd asks.
"Well, I guess you now know what it feels like to be treated differently," Lloyd says as he and Y/n throw their weapons on the table.
"Look, this is serious. If we don't turn big so that we can use our Spinjitzu, we don't stand a chance to against the Grundal," Zane says.
"But Lloyd and I already know spinjitzu," Y/n says.
"Yeah, but the two of you don't know the Grundal. We all need to be at full strength. What we need to do first is to find someone who might know more about how to defeat one of those things," Kai says before Lloyd sees a kid reading a Starfarer comic.
"Lloyd, focus," Cole tells the boy.
"I am. I think I know just the guy."
They walk to Doomsday Comix and enter the shop.
"You brought us to a comic book store?" Cole asks.
"Trust me. If there's anyone who knows how to defeat a monster that doesn't exist, I know just the person to talk to," Lloyd replies.
"We're not coming to pick out your stupid comic, Lloyd! This is serious business," Kai says.
Jay grabs a comic and gasps. "Oh, look. A first edition 'Daffy Dale.' I used to love that nut growing up," Jay laughs before clearing his throat and putting the book back. "So juvenile."
Lloyd then leads his friends to the register. They see a man with a ponytail and a beard.
"Fellas, meet Rufus McAllister, AKA Mother Doomsday."
"Well, if it isn't Lloyd 'Hemorrhoid' Garmadon," Rufus says. "Sorry if you came looking for the latest 'Starfarer,' I'm all sold out."
"Wh—Sold out?" He screams as everyone looks at him. "Oh, actually, Mother Doomsday, we need help."
"Well, color me intrigued."
"We have a problem. There's a Grundal on the loose and we need to know how to deal with it."
"Oh, a theoretical question."
"Yeah, theoretical. Can you help?" Lloyd asks.
He lowers his seat before coming out from behind the register.
"Dromaeosaurid Theropod Grundalicus. Phew! Although extinct, there has been a plethora of film, television and comics exploring the mythology around the primordial predator," He says as he shows them a comic about the Grundal before putting it back on the shelf. "Supposedly, they always get their prey."
"Sounds like he knows his stuff."
"Is there a way to stop it?" Y/n asks.
"First thing you need to know is its thick shell-like hide is invincible to swords, scythes, nunchucks, and throwing stars. So your cheap imitations will do nothing to slow him down."
"Good to know," Y/n says.
"Swell."
"Second of all, it's nocturnal and will only hunt at night."
"Oh, good. It's still daylight, so we can relax for a bit," Jay says as Rufus looks at them suspiciously. "Uh, I meant theoretically."
"And the only way to defeat it is with light. Like a vampire, with enough of it, it could potentially destroy him," He says before they walk to a display. "If I had my weapons of choice, may I recommend the Illumisword?" He asks as he opens the display to show four purple blades. "These are authentic replicas that would come in handy were you to live long enough to actually face a Grundal. And if swords are your thing," He says before pointing to another case with the ninjas gis inside. "Maybe I can interest you in an authentic ninja gi, signed by the very Ninja that saved the city."
"Uh, we'll just take the light swords," Kai says as his hand reaches out for the sword.
"Not so fast. This 'Starfarer' combo pack can only be won in the Fritz Donogan Trivia Battle Royale. You have what it takes to be the best?"
"You can do this, Lloyd," Jay says.
"Sign me up," Lloyd said confidently.
"Great," Nya says as she puts the phone back. "Now Lloyd and Y/n are missing. What's next?"
The phone rang and Nya plays the recording.
"Sensei, we're at Doomsday Comix. Garmadon's turned the others into kids and we're about to face a real life Grundal. If you get this message, this isn't a prank. Come quick!" Lloyd's voice says.
"Oh, dear. Well, there's only one person who could help return the Ninja back to normal," Wu says.
They then arrive at Jamanakai village. They stop in front of Mistake's Tea Shop and go inside.
"Hello, Mistake. We need a special tea," Wu says.
"They're all special, you old fool!"
"But this one can turn someone..." Nya says before clearing her throat. "Older."
"Ah, you seek Tomorrow's Tea. I only have one in stock in back. Follow me."
"It should be here," She says when she enters the back room.
"It's gone?" Nya asks.
"Just misplaced. I know it's here somewhere."
"We need to find that tea before it's too late."
"It's down to the final two. This question is for Lloyd," Rufus says.
"Lloyd! Lloyd! Lloyd!" The crowd chants.
"What is Fritz Donogan's famous catchphrase?"
"'Fear? Fear is not a word from where I come from!'"
"Correct! We're all tied up," Rufus says as everyone cheers.
"It's getting dark. The Grundal will be on the prowl soon," Zane says.
"Don't worry. I got faith Lloyd can win those Illumiswords," Kai says.
"Unless they ask him about the latest issue. You should have let him read it," Y/n says.
She was feeling very anxious.
"Is this really the best time to be eating cotton candy?" Kai asks Jay.
"It makes me feel young. Deal with it."
"Final question. The first person to answer this will win," Rufus says. "In the latest issue of 'Starfarer,' how did Fritz Donogan escape the imperial sludge?"
"I told you," Y/n tells her older brother.
"But I haven't read the latest issue," Lloyd says.
"By reversing the polarity of the ship's gravity transducer."
"We have a winner!"
The lights shake and the power then goes out.
"Oh, dear..." Y/n says.
"Who shut off the power?" Rufus asks.
"It's here," Kai says.
"What's here?'"
"You know that theoretical discussion we had earlier?" Jay nervously chuckles.
"Not the..." Rufus says before the glass cracks and the Grundal looks down. "Grundal!" He yells.
"We've got to get out of here," Zane says as they try to open the door.
The sign that had fallen down jammed the door..
"The door is jammed, we can't get out!"
"Look! It's coming!" Jay screams.
The Grundal then falls into the store after the glass breaks.
"We're doomed!"
"Doomed as Britts Subskian in 'Phoenix War' page 15," Rufus says.
"Not now!" Y/n yells.
"Quick! This way!" Jay yells as they get the swords and gis.
"Hey, McNasty, I thought Ninja were on your menu!" Cole says, grabbing the Grundal's attention.
They wave the swords as the light causes the Grundal to back off slightly.
"It's working!"
The ninjas then try to strike at the Grundal, but the swords break.
"Stupid toy!" Cole says, striking at the Grundal's leg.
"Uh oh!"
"Oh. We got a problem, guys," Jay says as the Grundal knocks them to register.
"Not to worry, I'll take care of this," Lloyd says as he and Y/n use their powers.
The Grundal backs off from the intense light created by Lloyd's and Y/n's energy balls.
The Grundal then uses its tail to knock Lloyd and Y/n.
"Oh, gross!" Kai says.
"This is the end, isn't it?" Cole asks.
The front door is then kicked open and Nya and Wu enter.
"Everyone out!" Nya says as everyone runs away.
"Use this!" Wu says as he throws a jug at them.
"What is it?" Jay asks, catching it.
"It'll turn forward the hands of time, turning you old and reducing the Grundal back to dust and bones," Wu explains. "But be careful, there's no turning back."
"Grundal, prepare to be extinct!" Jay says.
"No, wait," Cole says, stopping Jay. "What will happen to Lloyd and Y/n? They'll grow old too."
"Just do it".
"You'll miss out on the rest of your childhood, dude!"
"We can't do that to you. It's not fair!"
"Oh, for god's sake! Do it before I do it myself!" Y/n says.
The Grundal then knocks Cole's sword out of his hands.
"Oh, no!"
The Grundal tries to chomp them and they fall, causing the tea to land in Lloyd's lap.
"Just do it," Y/n tells Lloyd who nods.
"Fair? Fair isn't a word from where I come from," Lloyd says, standing up before throwing the tea at the Grundal.
The Grundal growls in pain.
"He used it!" Wu says as the Grundal spins, skin dissolving away.
"And it's working!" Nya adds.
The Grundal turns back to a skeleton before the ninjas turn back to their adult selves.
"What happened? We're not kids anymore," Cole says.
"It worked!" Nya cheers.
"They are the real Ninja," Rufus says, shocked.
"But what about Lloyd and Y/n?" Wu asks before the two people stood up.
"We're older," Lloyd says, voice a little deeper.
"The time for the Green and Purple Ninja to face their destiny has grown nearer."
"We're ready," Y/n smiles.
"Damn, my sister has curves now?" Kai asks himself.
"And closer to your height," Y/n teases before Kai smacks her gently. "Rude."
They prepare to leave before Rufus stops Lloyd. "Here you go, Lloyd. You can have my copy of Starfarer," He says, sniffling a bit. "You deserve it."
"That's okay," Lloyd says, lowering the comic book. "I already know how it ends," He says before holding Y/n's hand as they catch up with their friends.
There comes a time when we all must grow up. When that time comes, it's important not to forget the lessons of our childhood because our childhood is the greatest training one can ever have. Yes, the time until the final battle has grown shorter, but the Green and Purple Ninja have grown stronger.