Stuck on a precarious peak, the kids secretly search the plane for the final clue about Della's mysterious disappearance.
The family heads to Monacrow for a vacation while Donald Duck stays home to continue fixing the houseboat. On their way, the kids recover shredded pieces of documents from the McDuck archives on Della Duck and the "Spear of Selene", and try putting the documents back together before Scrooge McDuck can find it. However, Scrooge, while flying the plane, crashes the Sun Chaser into a peak, and one of the pieces slips away during turbulence. Unable to lift without damaging the engines, the aeroplane can't fly them off it, leaving the group suspended on top. Bentina Beakley then chides Scrooge for putting the kids in danger.
Noticing the piece slipped into the jeep's window, the kids distract Scrooge and Beakley while Dewey reaches for the piece. Launchpad McQuack mishears them and drives the jeep towards the other side of the Sun Chaser, causing the aeroplane to tilt towards the side and the plane door to open with Launchpad at the edge of it. Beakley gets the kids to the other side while Scrooge rescues Launchpad, but Scrooge orders the kids to stay in their seats for balance. Launchpad entertains the kids with a tape of Darkwing Duck stuck on the theme until they can figure a solution. Scrooge confidently attempts to fix the plane against Beakley's concerns for the kids until Beakley pleads with Scrooge to admit he can't fix everything, and Scrooge to slip nothing bad will happen to "her" before correcting himself.
Meanwhile, Dewey tries to retrieve the piece from the cockpit. Huey moves to the other side to counterbalance the plane as Webby coordinates the two in the right direction. Right when Dewey retrieves the piece, however, he is spotted by Scrooge and Beakley. Scrooge then demands Dewey give him the paper but it is blown away so Dewey chases after it into the cargo, and followed by Scrooge, where the added weight tips the plane to their side. Dewey then rushes to the piece now caught inside the propeller. Dewey reaches for the piece with Scrooge close by trying to save him. Dewey only comes back with Scrooge when he demands the truth of the Spear of Selene.
Scrooge then reveals the whole story: ten years ago, he, Donald, and Della were seasoned adventurers who had visited just about every possible location on the globe. Before the triplets hatched, Della wanted to embark on a journey to the new frontier — outer space. Donald thought the trip would be too risky with Della's sons about to hatch, and while the two argued about it, Scrooge built the rocket dubbed the Spear of Selene so he could reveal it when the triplets were born. Della, however, took the rocket on a test run before Scrooge could surprise her, the photo of this event on the very piece Dewey was retrieving. Della then braved into a cosmic storm, but despite her confidence, she was struck by a lightning bolt and stranded in space. Heartbroken, the boys accuse Scrooge of leading Della into that storm, leading Scrooge to become frustrated with everyone while the Sun Chaser falls from the peak. Thankfully, the fall isn't too high and the aeroplane survives, though Launchpad successfully crashes it a bit.
At the manor, Donald has rebuilt the houseboat and sees the bitter triplets who inform him they learned the truth, and solemnly prepare to leave the manor. Webby, Beakley, and Duckworth take a vacation away from Scrooge who is scolded by Beakley before leaving. Now alone again, Scrooge, reminiscing his countless efforts and failures in trying to find Della while the others' accusations echo in his mind, coldly states he is happy this way.
- David Tennant as Scrooge McDuck
- Danny Pudi as Huey Duck
- Ben Schwartz as Dewey Duck
- Bobby Moynihan as Louie Duck
- Kate Micucci as Webby Vanderquack
- Beck Bennett as Launchpad McQuack
- Toks Olagundoye as Bentina Beakley
- Tony Anselmo as Donald Duck
- As of this episode, six months have passed since the events of "Woo-oo!".
- The ending shots of Scrooge in his chair recreate the first panels introducing the character in Christmas on Bear Mountain.
- The Maltese MacGuffin is a play on a MacGuffin, an object or plot device that drives the story, and the 1929 detective novel The Maltese Falcon, in it was the eponymous statue providing the story's MacGuffin. Huey even references this by asking if the artifact is a statue.
- Della's disappearance has grim inspiration from her fate in the Dutch comic 80 is prachtig.