Scrooge was on his submarine, atop the sail/conning tower, talking to Donald. "I run a multi-trillion dollar business. I can handle a few juveniles for the weekend. You just focus on this new job of yours. Besides, I got a pretty low key day planned."
"Hoist the mast sail! Other boat words to Atlantis! Dive! Dive!" Dewey says, a tad to eager.
"No, wait!" Scrooge tries to save.
"Aye aye." Launchpad reports as he set the submarine to dive.
"Launchpad, the hatch! Stop the bjjbjbuadkjfo!" Scrooge warns as he gets a beak full of water, just managing to close the hatch.
"Woohoo!" Cheers an oblivious Dewey, who runs past an annoyed Rebecca who is squeezing water out of her hair, having been standing right under the hatch and thus got drenched.
"Talk to yer uncle." Scrooge tells Louie who is helping pump out the water with Webby.
"Hey Uncle Donald. Nope, yeah, pretty boring. We napped, rubbed ointment on our joints, old people stuff." Louie lies.
"What about the dragon? And the plane crash? And..." Webby starts to question
"Whoops, 3pm, time for dinner. Bye." Louie saves, ending the call.
"Well, why didn't you tell him the truth?"
"You didn't tell your grandma we were going to a dangerous underwater city, did you?"
"Ah, I, kinda sorta, didn't tell her anything?"
"Webby, that's irresponsible! She'll be worried sick. Call your grandma this instant, and tell her that you are spending the night at a friend's house, okay? Lying, it's the responsible thing to do."
"Launchpad, have yew ever piloted a sub before?" Scrooge asks.
"I sunk a helicopter in a wading pool, once. Same thing?" Launchpad asks.
"Uh, ae've done more with less. No matter, ae'm back! Uncharted territory, bold new discoveries..."
"Travel bingo! I love road trips. I've got snacks, a playlist of traditional sea shanties, matching family road trip shirts..." Huey cuts in.
"I appreciate the enthusiasm, but there's no time."
"But according to the travel itinerary..."
"Booooo! Adventure isn't about planning, it's about doing. So, what can I be in charge of? The buzz saws?" Dewey bombards Scrooge with questions.
"No." Scrooge says.
"Sonic Cannons?"
"No."
"Hyper dense zero-point energy missiles to pierce the scaly hide of a kraken?"
"None of those things are real things. This is yer first expedition so just stand back and watch an old pro from a safe distance."
"So what is this submarine equipped with?"
"Seat belts." Scrooge chuckles.
"Hah, good one. Classic Scrooge/Dewey banter: the seasoned but tired explorer passing the torch to his cocky young successor."
"I'm pretty sure he doesn't actually know our names," Huey says.
"I'm sorry, what?"
"I think he called me Herbert, once."
"Don't be ridiculous. Hey Scrooge, when are we going to set sail, Scrooge?"
"In a moment, Sonny Jim." Scrooge says as he works on a map. At this, Huey offers Dewey a shirt.
"I will cram it down your throat." Dewey threatens Huey.
"Dewey, don't kill your older brother." Rebecca scolds.
"Guys, lighten up. We're on a deep sea expedition with Scrooge McDuck." Louie reasons.
"Mr. McQuack, chart a course. Next stop, the Lost City of Atlantis!" Scrooge exclaims.
"Woohoo!" All the kids cheer.
"In about sixteen hours!" Scrooge adds, ruining the excitement for the kids. Except for Huey.
"Shanty time!" Huey cheers, to which Rebecca sighs and rolls her eyes.
Hours pass as the shanty tape plays, everyone falls asleep, save for Dewey and Rebecca. Rebecca was meditating, eyes closed as she sat lotus position in her seat, hands on her knees. However, Dewey was getting more and more agitated.
"Driving! Piloting! Driving! Right!" Launchpad says to himself.
Dewey goes up to Scrooge, who is working on the map still. "Hey Scrooge, first mate Dewey, here. Your map's got us going the long way. I could probably find a shortcut if you let me..." He reaches for the map, but Scrooge snatches it away.
"Ah ah ah, lad. The shortest distance between two points isn't always a straight line," Scrooge states.
"Okay, but yes it is. So if we just go..." Dewey reaches for the map, but Scrooge smacks him away. Then, when Scrooge is disctracted, Dewey takes the map and erases Scrooge's route, replacing it with his own.
"Driving! Hm?" Launchpad sees the changes, and immediately alters course as Dewey takes a seat again.
"Shortcut achieved." Dewey says confidently.
"Dewey..." Rebecca says, knowing what he did.
"Relax, he'll thank me later."
Later, the sub is attacked several times by various enemies along the way. They just finish up getting rid of the giant squid that had attacked them.
"Yew kids are the death of me." Scrooge says, highly annoyed as they lay on the ground, exhausted.
"Dewey. Dewey will be the death of you." Dewey says, which gets him smacked upside the head by a twitchy-eyed Rebecca. Scrooge is erasing the route Dewey drew.
"Could we make a pit stop? I'd use the bathroom but it's, um, occupied." Huey asks, given a sea monster is in the toilet.
"For the love of, It's the middle of the ocean, there are no pit stops." Scrooge says.
"How about that conspicuously unmarked tanker?" Launchpad points out.
The kids look at Scrooge, all seeming to need it. "Ack, fine! Launchpad, pull us up alongside it."
"Oh thank you uncle Scrooge!" Rebecca says, feeling bound to bursting.
One bathroom break later...
Rebecca sighs in relief as she leaves with her brothers, following Scrooge back to the sub. She then looks down. "Ah, Dewey, you got some toilet paper sticking to your, um, foot."
"What?" Dewey asks as he looks, hopping around to get it off and stumbling some as they get back to the sub, which they reach in time to avoid a rough storm over...
"The Drake Barrier Reef. Powerful currents combined with rocky terrain make it nearly impossible to navigate, but on that rare occasion when snow falls above the reef, the currents cool allowing safe passage to..." Scrooge starts to explain.
"Are we there yet?" Louie cuts off.
"Ae was just trying to..."
"Right side of the left?" Huey asks.
"Just let me..."
"Guys can you let uncle Scrooge..." Rebecca tries to cut in.
"Look! There that thing is. We found it
"Whoa." All but Rebecca and Scrooge say in awe.
"Yes, good, Atlantis, 'ooh,' 'aah,' thanks for spoiling the moment." Scrooge says, annoyed.
"Some people just can't learn patience." Rebecca sighs.
"The whole place is upside down." Huey point out as, indeed, the entirety of Atlantis is upside down.
"Ah, well that's a new one." Scrooge admits as the sub enters into an air pocket.
"Woah." Dewey says in amazement as Webby and Louie are up to, something else.
"Just call your grandma already, it's no big deal. Remember you're at a friend's house, okay? You got this." Louie tells Webby, who answers her phone.
"Hi granny, I'm spending the night at a friend's house and nothing is wrong!" Webby spouts off rapidly before hanging up.
"Oh, you don't got this." Louie realizes, cringing while Rebecca facepalms.
"Ah, according to these markings, the Atlanteans were so eager to build their epic city of wonders and death traps, they didn't stop to figure out a proper support structure and the whole thing fell into the sea." Scrooge explains.
"Uh, why did they write all that before the city collapsed?" Rebecca points out the oddity as the writings depict the collapse, somehow.
"Either way, you kids best stay by the sub while I scout ahead." Scrooge suggests.
"Dewey ran in as soon as you said 'death traps'," Huey points out.
"C'mon, Scrooge! We got this!" Dewey calls out.
"Dewey stop!" Rebecca demands as she chases after her reckless brother.
"Oi!" Scrooge follows as he mutters, worried for them as the others follow, quickly catching up, even after Launchpad thinks he heard something. "Lad, lass, ae thought the traps would get yew fer sure."
"Uh, about that..." Rebecca says nervously, as a grumpy Dewey points up.
"Stupid upside down temple. Nothing cool about walking under buzz saws."
"Except not dying." Rebecca says.
"From now on, don't touch anything." Scrooge orders, after which Dewey kicks a rock which hits a panel, releasing snakes from a pit trap onto Launchpad, biting him, which the kids panic at. "Maybe Atlantis was an ambitious first outing."
Scrooge soon leads ahead, coming across a rope bridge guarded by lasers, Rebecca and Dewey keeping pace.
"Woah, suspension bridge, chasm, glowing blue mystical lasers? Classic." Dewey says in aw, ready to cross, but is stopped and pulled back by Scrooge.
"Even a basic death trap still has the word 'death' in the title." Scrooge demonstrates by interrupting a beam, at which a jet of fire erupts, engulfing the bridge.
"We'll find another route; it's not safe for amateur adventurers." Scrooge says, starting to walk away with Rebecca.
"That sounds like a challenge." Dewey says, looking at the bridge.
"Dewey..." Rebecca says.
"Ae have to stress that is not a challenge." Scrooge clarifies.
"...is exactly what you'd say to dissuade the weak of heart from accepting the challenge, well challenge accepted." Dewey, somehow reasons.
"There is no challenge!" Scrooge warns.
"Dewey stop!" Rebecca calls out.
Dewey slowly dances across the bridge, hitting every single laser as he scats and sings.
"Oh I can't watch!" Rebecca covers her eyes, not wanting to watch her brother perish horribly.
Somehow, Dewey isn't incinerated as he gets to the other end. "Nailed it!"
Scrooge adjusts his top hat and uses his cane to zip line across, faster and safer than Dewey did.
"Sure, if you wanted to do it the easy way." Dewey says.
"Why wouldn't you want to do it the easy way?" Scrooge questions. "Yew need help lass?" He calls to Rebecca.
Rebecca takes a breath before leaping through the lasers, action movie style, avoiding every last one until she lands perfectly on the other end. "THAT is how you dodge lasers, Dewford. Five years of gymnastics really pay off!"
"Well done lass. See lad? Even when working harder, yew still need ta work smarter."
"Lad? I don't call you old man or Scotty McTophat." Dewey says.
"Dewey!" Rebecca scolds.
"Respect yer elder. When yew adventure with Scrooge McDuck..." Scrooge scolds.
"But I'm not. You want me to adventure 'behind' Scrooge McDuck or wait by the sub. I might as well be back on the houseboat." Dewey argues.
"Because yew have no idea what yer doing." Scrooge counters.
"So show me. Give me a chance instead of lumping us all together in the back seat while you drive."
"He's not lumping you guys together."
"Oh really, which triplet am I?" Dewey asks.
"It's..." Scrooge hesitates. "Bluie?"
"Uncle Scrooge!" Rebecca gasps in disbelief. He really didn't know her brothers' names? Suddenly, a massive jet of fire shoots up and destroys the bridge.
"Aw fantastic. Yew see what ae'm talking about?" Scrooge groans as the others get to the bridge. "Yew four find another way around, we're going to..." He realizes Dewey is climbing down ahead of them. "push onward, apparently."
"Dewey!" Rebecca follows after her brother, groaning.
Scrooge, Rebecca, and Dewey make their way down, Scrooge still miffed by Dewey's recklessness. "Maybe ae could just hire some family. Then they have to listen to me."
Rebecca looks at him, a tad hurt.
"Oh but, not yew lass. Yer fine." He assures Rebecca with a soft smile as they reach an area overlooking the treasure chamber.
"There she is: the jewel of Atlantis." Glomgold says as he grabs the red glowing jewel before sinisterly laughing.
"Who's that?" Dewey asks.
"Flinheart Glomgold: the poor man's version of me, which to be fair, still makes him insanely rich." Scrooge explains.
"Emphasis on 'insane'. The man is a lunatic." Rebecca adds.
"Load up the sub." Glomgold orders as Donald is dragged in.
"They got Uncle Donald." Dewey gasps.
"What?" Scrooge gasps in disbelief as Dewey slides down the mound of coins, Scrooge diving into the treasure as Rebecca sneaks around.
"Let go of my uncle!" Dewey demands.
Glomgold turns and faces Dewey. "No."
"I wasn't prepared for that." Dewey confesses, as Scrooge surfaces and pins Glomgold, Rebecca ready to help, hiding.
"What are you here, Flinty?" Scrooge asks.
"What are you doing here, Scrooge? I told you to keep the boys safe." Donald says.
"Aw, they're perfectly fine." Scrooge assures.
"Oh yeah? Where are the other two?"
"Back safe in the room with fire and the snakes."
"What?" Donald gapes, as Rebecca face palms.
"Ah Scroogie, I see you know my newest employee." Glomgold half-gloats.
"Your new job is with my sworn enemy?" Scrooge questions.
"I can't keep track of all your sworn enemies." Donald argues.
"Now, now, Donald has been a model employee and an excellent prisoner." Glomgold states.
"Yeah. Wait what?" Donald finds himself grabbed by the mercenaries and a knife at his throat. Rebecca tries to act, but is grabbed by Gabby.
Scrooge quickly lets Glomgold go. "Hiring my own nephew in order to use him against me? Now that is good planning." He admits as the mercenaries leave with Glomgold, tossing Rebecca and Donald back in. Scrooge rushes to Rebecca. "Yew okay lass?"
"Yeah, I'm fine."
"Have fun being the second richest duck in the world, for the next five minutes." Glomgold gloats, laughing as Gabby throws a blade at a pressure switch, which causes the crystal on top of the chamber to glow and the room to start flooding, the door closing behind Glomgold and his team.
"I'd like to point out that this trap was not my fault." Dewey says.
As the room floods, everyone grabs onto something to float on as Donald tries to plug the flow, failing. "Oh no. I knew it. I knew I couldn't trust you with the boys."
"Not the time, Donald." Scrooge says.
"Crazy old man. All you care about is the next adventure. This is the Spear of Selene all over again." Donald complains.
"I was not responsible for the Spear of Selene." Scrooge argues.
"Stop. Scrooge was trying to keep me out of trouble, but I was so caught up in- why is there a lamp on the floor?" Dewey notices.
"What?" Donald looks confused.
"Atlantis is upside down. That means that lamp was supposed to be on the floor surrounded by all this treasure."
"At a boy, lad. Keep going." Scrooge encourages.
"C'mon Dewey, show you aren't just an airhead." Rebecca adds.
"But why would you surround that thing with treasure unless..."
"That's the real jewel of Atlantis!" Dewey, Scrooge, and Rebecca figure out.
"That thing lit up when the trap was sprung. I bet my bottom dollar it's the power source that runs the city." Scrooge recons.
"Uncle Donald, you gotta let the room flood so I can grab the jewel." Dewey states.
"That's crazy, as opposed to what, let go? Trust you?" Donald argues
"Well yeah, that's kinda all you can do. This is a surprisingly insightful death trap." Dewey points out.
Donald relents and unplugs the leak, the chamber filling with water rapidly. When they can reach it, all four pull and wrench the jewel from its socket, the water going back down again as the trap deactivates.
"We're going to be okay." Donald says.
"Phew!" Rebecca exclaims.
With that, Donald finally notices Rebecca, looking at her with shock. "Who, is..."
"Donald, this is Rebecca Duck, the boys' older sister..." Scrooge says, smiling.
"What?!" Donald looks at Rebecca in shock, had somehow forgotten he had forgot the fourth egg after 10 years of raising three boys. And also maybe surprise Scrooge cared for her at all.
"Um, hi, Uncle Donald." Rebecca waves nervously.
Donald's demeanor changes to elation as he pulls her into a hug. "Oh Rebecca honey! It is so good to finally have you back."
Rebecca hugs back, smiling. Finally, a completed family, as she had wanted for so long.
"Now let's go!" Scrooge declares, rejoining the party who are still fighting the mercenaries.
"Oh yeah, those guys. Huey and Louie are doing okay," Donald says.
"Surprisingly so," Rebecca comments.
"Wait, where's Glomgold?" Scrooge asks, noticing him not there.
Then, the mercenaries are interrupted by Glomgold over a walkie-talkie. "Hey team. Wanted to thank you for keeping Scrooge's kin busy while I escape with the jewel and blow up Atlantis with my most hated rival inside."
"But I thought employees were greatest treasure of all." Hack argues.
"Don't be ridiculous. Treasure is the greatest treasure of all. That's why it's called treasure. Glomgold out!" Glomgold states as he opens fire on Atlantis with torpedoes.
"We have to go." Scrooge says as he calls on the others.
Then, Gabby grab's Donald's wrist. "Mr Duck, could we ah maybe bum a ride with you?" She asks nervously.
Donald, with an 'are you serious' look. Then, we cut to the sub, where the others are piled on top of the mercenaries.
"That was some quick thinking. You just may be an adventurer yet, Dewey." Scrooge says.
"Yes! You remembered his name!" Rebecca cheers.
Eventually, the sub arrives and interrupts Glomgold's press conference, with Scrooge taking all the attention. It also turns out the jewel Glomgold took was cursed, as a kraken tentacle grabs him and hauls him away.
"Curse you McDuck!" Glomgold cries out.
Then, Beakley arrives. "Webby? Uncle Hampus?"
"How long?" Louie asks.
"The whole time."
"Granny, I can explain." Webby starts.
Beakley just smiles. "Dear, you are safer in a sunken city with Scrooge McDuck than you are locked in a vault in Fort Knox. No more lies, and you can go with him wherever you like."
"Yes!" Rebecca cheers and hugs her honorary sister. As this happens, Scrooge and Donald are talking.
"Now Donald don't..." Scrooge starts.
"Stop, I admit I'm a little overprotective," Donald says.
"A little?" Louie questions the understatement.
"No matter what I do these boys will get into trouble so maybe you can teach them how to get out of trouble," Donald proposes.
"Uncle Donald?" Huey asks optimistically.
"It might be okay if the boys see you, and especially their sister, every once in a while, if not regularly." Donald says.
At that, Rebecca gasps, eyes wide and glistening. "Really?"
"Some times like birthdays, or federal holidays, nothing too..." Donald continues, but...
BOOM
Everyone looks in the direction of Donald's boat, which has blown up because the engine overheated.
"Ooh, I may have left the engine running in the houseboat." Dewey confesses as everyone scowls at him.
"How do you forget that detail?!" Rebecca asks, frustrated at her brother still being a little, scatterbrained.
Ian, having made his way to the docks after snapping out of his trance, sees the scene and looks at the burning boat, then to the family. "I can help fix that, if you want. I have a book or two on boatbuilding."
"And I may have a dozen or so spare bedrooms in the mansion." Scrooge adds.
"Yay!" Everyone cheers, Rebecca nearly tackling Scrooge in a thankful hug.
"Thank you Uncle Scrooge! I finally get to be with my baby brothers!" She cheers.
"There you have it. Reclusive adventure capitalist Scrooge McDuck is back with family in tow solving mysteries and rewriting history." Roxanne reports.
At the manor, a crane operated by Launchpad is lowering the still smoking houseboat into the pool, Donald guiding Launchpad.
"Little to the left, no no no!" Donald cries out as Launchpad outright drops it.
"Did I do it good?" Launchpad asks, oblivious.
Meanwhile, the kids are helping clean the garage with Ian in the wake of everything, the otter eager to have found one job that will keep him busy for a while. Dewey eventually finds himself back at the painting they found before, alone. Curious as to the folded corner, he carefully pushes it back up, revealing a female duck with short white hair, dressed in a pilot's outfit, fighting a pirate on the mast. At this, Dewey goes wide-eyed in shock. "Mom?"