At the docks of the Money Bin, Huey, Dewey, Louie, and Webby prepare for their day-long boat trip. The boys are excited to begin the trip as they reminisce of all the times they got in trouble, especially the time Louie got them lost, earning him the nickname "Captain Lost", while Webby is excited about beginning their first about trip together. As they set sail however, it appears that the boat can only hold three passengers. Unwilling to disappoint her friends, Webby (dejectedly) volunteers to stay behind, despite the boys proclaiming she should come. Once they depart, Webby notices a message in a bottle containing a call for help. Noticing a trail of more bottles, Webby takes the call to action to help the person in need.
After tracking down the bottles' source to an amphitheater, Webby encounters a teenage duck named Lena, who was writing the messages for fun. Lena takes interest in Webby's spunk, and the two get along well. Lena then suggests going to a party that she knows about, with Webby agreeing to tag along.
Later, the girls arrive at a junkyard. Lena asks Webby to help her get in, although Webby is confused as to why they would need to do that if Lena was already invited. Lena the reveals she wasn't invited. Nevertheless, she manages, and the ducks make their way through the junkyard. At the center, Webby discovers that the place is swarming with Beagle Boys gathering for Ma Beagle's birthday. Webby urges Lena to get out of this place, but they bump into Bouncer Beagle, who decides to give Webby to Ma Beagle as a birthday present. Lena sneaks up onto the podium where Ma Beagle is and pushes her birthday cake into the beagle's face. Angered by the prank, Ma Beagle orders the boys to capture them as the ducks run away.
Webby and Lena escape to the alleyways of Duckburg, Lena and Webby just barely escape, noting they almost died. Just then, the Beagle Boys spot them and drive a truck towards them; fortunately for them, the truck is too big for the alley way they ran into and Webby finds a fire escape ladder, and the two ducks escape to the rooftops. They overhear a set of the Beagle Boys with a radio to Ma Beagle notifying where they are. To cover their tracks, the girls pretend to be a British offset of the Beagle Boys called the "Beagle Birds" and successfully commandeer the radio from them. Happy over their feat, the girls decide to celebrate their escape at a nearby playground. While conversing with Lena, Webby brings up her relationship with the triplets. Lena disparages this by mentioning how exclusive the boys are towards her; at that moment, Huey, Dewey, and Louie show up looking for Webby, wishing to apologize for disappearing for 4 hours and explained Louie got them lost again. Before the kids can discuss things further, a group of clown-esque Beagle Boys show up and corner the kids. Regrouping, Webby and the triplets try to devise a plan. However, Lena decides to leave the kids to escape the Beagles and urges Webby to come with her. Ultimately, Webby chooses to stay with the boys, thus a disappointed Lena takes her leave. Consequently, the kids incapacitate the Beagles with banana peels the triplets had from earlier.
Assuming Lena had abandoned them, Webby becomes morose over losing a friend. Regrouping at the docks, Huey consoles her and promises to never leave her behind, but they shall leave Louie, he is useless at the situation. Then Webby notices another message in a bottle, this one containing a letter from Lena revealing that she was captured by the Beagle Boys as revenge for ruining Ma Beagle’s birthday. Despite what happened before, Webby declares that Lena's still a friend in trouble, and she enlists the triplets to mount a rescue mission. At the amphitheater, the Beagle Boys are holding Lena captive. Webby and the triplets sneak around by boat and try to untie Lena in time; however, they end up getting spotted by the Beagles and all the ducks are captured.
With Lena and Webby tied up next to each other, the Beagles celebrate the capture as Ma Beagle heads over. Lena chastises Webby for getting herself captured, although when Webby argues with her. Enraged, Webby and Lena argue and criticise each other for what happened to them this night. Then the two then realize they can use the Beagles' ties against them. They ask the Beagles who gets to hand them over to Ma Beagle; as none of the Beagles are willing to share the victory, the Beagle Boys end up brawling each other, buying the kids time to escape. Soon after, Ma Beagle shows up and, noticing the Beagles came empty-handed, revokes celebration of the Beagle Boys' birthdays as punishment.
Back at McDuck Manor, Lena bonds with Webby and the triplets as they bid farewell to Lena. Once the kids depart, Lena returns to the amphitheater. There, she uses her talisman to summon her aunt, Magica De Spell, who is shadow (due to Scrooge banishing her to the shadow realm)to report that she has gained access to the McDucks as Magica smiles evilly.
- Kate Micucci as Webby Vanderquack
- Danny Pudi as Huey
- Ben Schwartz as Dewey
- Bobby Moynihan as Louie
- Kimiko Glenn as Lena
- Margo Martindale as Ma Beagle
- Eric Bauza as the Beagle Boys
- In the scene where Lena remarks that the triplets are exactly the same, Lena's purple eyeshadow disappears.
- When fleeing from the Beagle Boys, Webby and Lena pass a billboard sign that says "Beaks".
- The events of the episode are clearly based on the movie The Warriors.
- The episode was retitled "The Beagle Birthday Breakout!" for airings since May 2018.