Inside of a cabin on Woodchuck Island, Launchpad holds a speech for all the Woodchuck scouts, as he and Huey are dressed in their scout uniforms in the middle of a junior woodchuck graduation ceremony. In the audience, Webby asks Della about why Donald isn't wearing a uniform even though she's wearing hers, with Della admitting he was kicked out of the Junior Woodchucks due to his ill temper with nature, as Donald is seen aggravatingly swatting away a mosquito as proof. Launchpad then continues to explain that all the Junior Junior Woodchucks will now become Junior Woodchucks, Junior Woodchucks will now become Senior Junior Woodchucks, and this year the candidates for Senior Woodchuck include Huey Duck and Violet Sabrewing. Huey, however, is more so surprised that Violet is even a Junior Woodchuck since he's never seen her at any meetings, but Violet claims to have been focusing her time on the "real work" of woodchucking, as she then shows her hidden stripes of badges behind her strap.
Due to only one candidate allowed to be granted the title of Senior Woodchuck, Launchpad explains that both candidates will compete against one another in the most intense, mental, and physical trial of their skills, the Junior Woodchuck Wilderness Challenge. After the ceremony is concluded, Huey begins to have self-doubt about his skills, especially when he realizes he's not allowed to use his Junior Woodchuck Guidebook during the challenge. Nevertheless, Webby, Dewey, and Louie encourage Huey to do his best, as Huey and Violet leave for the challenge with Lena cheering on Violet in the meantime.
While Scrooge is gazing at a painting right above the fireplace, Dewey approaches him and asks him who the person in the painting is. Scrooge claims it to be a portrait of Isabella Finch, while Della adds in that she was a great adventurer and chief of woodchuck exploration. Scrooge states she was a legend when he was a kid, and he read about many of her adventures in one of the only books he had, The Collected Adventures of Isabella Finch. While talking about how she bested the Fever Beast of Tibet and swatted the Swiss Swarmy of Microbeesia, Scrooge climbed onto the shelf above the fireplace and ripped off a map that was originally thought to be a part of the painting.
Although the family was initially angered at him for putting damage to a respected painting, Scrooge believes Isabella hid the map on the painting so future adventurers could follow in her steps. while Scrooge talks more about the map, a strange bird noise is heard from a nearby window as Scrooge then shoo's the bird away, while he encourages everyone to listen to the song of adventure calling them. At the start line of the challenge, Launchpad gives Violet and Huey separate colored flags to place on designated trail-markers leading to the highest point of the island. At the peak, whoever places their flag on the final trail mark first will be crowned Senior Woodchuck.
As the race begins and Huey and Violet make their way towards the peak, Scrooge and the rest of the gang proceed on a different route using the map provided to them. Meanwhile with Huey, he encounters a dead end but manages to create a compass for himself to know where north is to proceed to the peak. He then comes across the next trail mark, but to his surprise he notices a purple flag has already been placed on the trail mark, as Violet mocks him from afar. Meanwhile Scrooge's group continues on with the path, but they are once again encountered by the bird making strange noises from earlier.
Dewey, however, is intrigued with the bird and even follows its movement as a dancing pattern. At the same time, Donald is still aggravated by the mosquito flying around him that he runs off the path to lose it as everyone including the bird follows him. Much to Scrooge's annoyance, he still decides to follow them while knowing they're getting off the track to the treasure. Meanwhile Huey begins to hear the sounds of thunder, as he recalls Junior Woodchuck rule thirty-eight "when you hear thunder, it's time to get under cover." However, Huey instead decides to press on in fear that he'll fall behind on the race if he waits for too long.
Suddenly, Huey is electrified by small sparks, as he realizes the rain is lightning rain. While trying to get to cover, Huey attempts to use a root of leaves as a shield, but he then witnesses Violet running by him with a hand-made umbrella using the same leaves. Violet gives him a useful tip of severing the rubber leaves at the base, but Huey still claims to have known it already as Violet continues on ahead. Meanwhile, Scrooge and the rest of the group are hiding under a log to wait out the storm, as Scrooge explains the rain is the lightning rain of Chimpopo that Isabella managed to withstand for a hundred and eighty-three days on the island. Della still tries to convince Donald that nature can be tolerable, but she herself loses her cool after having been shocked multiple times by the lightning rain.
Through one of the holes of the log, the bird shows up again, with Dewey deciding they should follow it with the hopes of leading them to another adventure. Meanwhile, Huey is patching himself up behind a large tree as the storm clears up, while he tries to remain confident even though he's gotten himself lost. He then tries to imagine the Junior Woodchuck guidebook that's in his mind, as an imaginary talking guidebook named J.W. Guidebook shows up in front of him. J.W. claims he's shown up to help Huey teach him things about both nature and himself. He then suggests to Huey that he uses the sun for assistance, which gives Huey the idea to place a stick on the ground to use the shadow as a reference to know where north is.
Although Huey has now regained confidence, he is interrupted when a bear shows up behind him. J.W. tells Huey to make himself big and intimidating, but although Huey stands on a rock and acts ferocious, the bear in return stands on two feet and easily overshadows him. He then attempts to flee from the bear but is blocked by a large tree, as J.W. reminds him of Junior Woodchuck rule forty-three "If a bear you spy, string your food up high." This gives Huey the idea to climb up the tree using its branches with a rope from his backpack, as the bear aims to catch him in the process but fails.
Luckily, Huey sees the next trail mark on the mountain beside the tree, but Violet still manages to catch up to him. Suddenly, one of the branches Violet was hanging onto snaps, causing her to fall on a branch low enough to be dangerous for the bear to catch her. In order to stop the bear, Violet cuts off a bee's nest attached to her branch, as it falls onto the bear and chases it away. Although the bear problem is solved, Violet has no other branch to climb up or down with, as J.W. then reminds Huey of Junior Woodchuck rule seventeen "A woodchuck looks after their fellow woodchucks, whatever the cost." Huey, however, decides to abandon Violet and proceed on with the challenge, excusing himself that someone else will come along to help her down.
Even though Violet believes he abandoned her because of her prior smack talk, a nearby woodpecker begins making small holes in the tree, allowing Violet to climb her way up while quoting Junior Woodchuck rule seven hundred thirty-two "Respect nature, and nature will respect you." Meanwhile with Scrooge's group, the bird continues to lead them to a large tree with a small entrance to a cave in between the roots. Scrooge still believes they should return on the proper path, but Dewey believes the bird is leading them the right way since it already lead them out of the storm.
Immediately after Scrooge begins turning back, the bear previously attacking Huey and Violet approaches him, as he recognizes it as the Nandi bear from Isabella Finch's cave of the bear clan. Despite Scrooge wanting to fight the bear, the bird snatches his map away from him and forces Scrooge and the rest of the group to run into the cave after it. Meanwhile, Huey finally manages to climb to the top of the peak, but is angered to realize the final trail mark is centered around a pit of lava. Just as Huey is about to cross the bridge to the trail mark, J.W. reminds him of Junior Woodchuck rule seven hundred twenty-six "Always check every bridge for stability."
Desperate to remain in the lead, Huey discards following the rules and runs across the bridge, but one of the logs snaps mid-way. Violet then calls for Huey to see if he's okay, as she notices Huey was able to grab onto one of the stepping logs of the bridge. as Violet helps lift Huey back up from the broken bridge, Violet swiftly gets back to work to make her own way across the bridge. Out of instinctive thinking, Huey ties his rope to a rock and throws it to attach it to a stick on the other end of the bridge. Huey then ties the rope to a stick on his end of the bridge and stressfully begins tight walking to the other side, while agitating himself on winning to achieve the Senior Woodchuck title.
Meanwhile, Scrooge and his group continue to chase after the bird, but they then come across three separate tunnels while unknown as to which tunnel the bird flew into. Scrooge begins to get agitated that they're being pushed away from the adventure they were already on due to the loss of the map, but Webby believes adventure isn't about following the same path, it's about trying new things and going off the map. Eventually, Scrooge decides to mimic the bird's sound and movement, which allows them to hear the bird's chirping coming from the right tunnel.
Meanwhile, as Huey is nearing his way towards the other end of the bridge, he notices from above that Violet had made herself a glider, in which she uses the evaporating air from the lava to fly herself over to the other side. Huey then pleads to J.W. for his help again, but J.W. tells him that the only person who can help him is himself. Instantly after saying that, J.W. is hit by a drop of lava and starts to burn, leading him to ask Huey why he would imagine something like that. Eventually the rope splits apart due to the lava bubble bursts and causes Huey to fall, but Violet manages to catch him just before he reaches the lava.
When Huey asks Violet why she saved him, Violet reminds him of the Junior Woodchuck rule "A woodchuck looks after their fellow woodchucks, whatever the cost," leading Huey to believe she really is a better woodchuck than him. They then both land in front of the trail mark, as Huey believes he's failed the Woodchuck oath by breaking the rules due to leaving Violet behind. Violet admits she's also failed before and shows Huey a failure badge she received, much to Huey's shock as he was not aware such a badge ever existed. She then states her three previous failures of attaining the role of Senior Woodchuck, while believing that failure is a logical and natural conclusion of trying something new. To cheer Huey up, Violet recalls Junior Woodchuck rule seven "Work harder, make yourself better, and try again."
Violet then proposes they both finish together so they may both become Senior Woodchucks, but Huey instead rejects the idea and allows Violet the win, believing she's earned it and he hasn't for now. This leads Violet to placing her final flag on the trail mark, which then causes the center of the peak to begin lowering. Both Huey and Violet then learn the center is actually an elevator, as it starts lowering both of them to the bottom of the inner peak. At the same time, Scrooge and his group come running in through one of the tunnels as Launchpad is seen awaiting everyone's arrival. Initially, Della believes Huey won, but Huey instead admits his loss, leading Della to become frustrated and protesting the challenge to be rigged.
Even so, Huey admits he lost fair and square, as he then asks Launchpad for his failure badge, which Launchpad decides to offer him one of his own. Launchpad then announces the newest Senior Woodchuck to be Violet, revealing her middle name to be Apollonia, as Launchpad gifts her a new strap with her fathers, Lena, Huey, Scrooge and his group cheering for her on her accomplishment. As the bird is seen once more in front of Scrooge, Huey then recognizes its chirping singing and believes it to be the Tittertwill Bird of Knowledge, the legendary mascot of the Junior Woodchucks and descended from the personal pet of Isabella Finch.
The bird then bumps itself onto a nearby metal Woodchuck symbol, where the symbol then suddenly twists and opens a secret compartment from inside the rocks. Dewey then realizes the bird wasn't distracting him and the group, but instead it was leading them to Isabella Finch's treasure. When Scrooge looks inside the compartment, he discovers a small box containing Isabella's lost adventure journal. Scrooge states the journal contains information of all the adventures she's been on for future generations to learn about. They then discover pages involving legends even Finch couldn't find such as The Stone of What Was, The Fountain of Youth, The Third Eye Diamond, and the Lost Harp of Mervana. Knowing that her journals contain resourceful information, Huey believes the journal can help them discover some of the greatest lost mysteries of all time.
While Scrooge and the rest of the gang show their excitement for new adventures to come, it is revealed that the mosquito bothering Donald the entire time is actually a mechanical spy bug. Its camera is seen being shown to agents of F.O.W.L. including Gandra Dee, Black Heron, Phantom Blot, and the Board of Directors. Through the camera, Black Heron points out their discovery to a journal holding access to the most mysterious relics lost to time, with Board of Director Bradford adding that the race is on.