It's a race between the Squirrely Scouts and the Cream Puffs to the top of Mount Doom. Will Timmy and his Dad's team survive this harrowing challenge, or will Mrs. Turner, Tootie, and the girls make them turn tail? There is a parent rivalry. (Timmy's parents are rivals.)
Timmy Turner is at his home preparing for his Squirrel Scout troop's hike to the top of Mount Doomsdale, a rite of passage that Timmy says will take him from "boyhood to older boyhood". He recites the Squirrel Scout Credo. Wanda is reluctant to the idea of coming with Timmy, since the woodlands is not a safe place for Poof, but Timmy insists since there will be no other stable adult around otherwise: his father, Mr. Turner, is in charge of his scout group. At that moment, Mr. Turner appears outside Timmy's window wearing the same flying squirrel costume he wore in "Who's Your Daddy?"? A gust of wind promptly blows Mr. Turner away, so Wanda agrees to accompany Timmy up the mountain.
Near a lake and mountain, Timmy and his other scout troop members, Chester McBadbat, A.J., and Sanjay, admire how peaceful the mountain looks, until Mr. Turner points out that the actual mountain is another, more scarier looking one nearby. Timmy is not that concerned, as long as he gets to make his passage into older boyhood in a girl free environment. At that moment however, a minivan pulls up and the Sugar Cream Puffs hop out, being led by Timmy's mother, who explains to them that she is the troop leader of the Cream Puffs. Tootie, also a Cream Puff member, is there, and greets Timmy by telling him she is there to make the passage from "girlhood to older girlhood" by hiking up the mountain, and that she also just earned her mouth to mouth resuscitation badge, before she starts making a kissing gesture at Timmy who runs away.
The Cream Puffs recite their Cream Puff Credo, which ends with the insinuation that they are "much tougher than a squirrel". Mr. Turner takes this a challenge, but Timmy claims that they are just girls dressed like dessert and cannot beat them. Both Mrs. Turner and Wanda are annoyed by this; Mrs. Turner slaps Mr. Turner with his glove to make a challenge, that the girls will beat the boys to the top of the mountain; while Wanda is annoyed at Timmy for underestimating the Cream Puffs simply because they are girls, and also reminds him that fairy magic cannot be used to cheat in competitions because of Da Rules. Cosmo says that he will help Timmy because he is a boy, but both he and Wanda are snatched up by a passing bird which mistook their caterpillar form for food. Poof starts to whimper, but Timmy presents him from crying by making faces at him. Chester thinks Timmy wasting time making faces at his "canteen", and points out that the girls have already gotten a head start. From a distance up the mountain, Tootie gloats that she will meet Timmy at the top.
Mr. Turner notices a trail of frosting on the ground left by the Cream Puffs, and vows that despite forgetting all their food and survival supplies, he will lead his scout troop to the top of the mountain. At that moment though, the rope that was keeping Mr. Turner (still in his flying costume) anchored to the ground snaps, causing Mr. Turner to be blown away in a gust of wind, and leaving the kids alone to fend for themselves in the wilderness. After taking a few steps, Timmy and his fellow scouts are ravaged by the wildlife. A.J. claim something with "beady red eyes" bit him, but it turned out to simply by a starving Chester. Sanjay complains that he has gotten poison ivy because they don't have knee socks like the Cream Puffs' uniforms do, causing the other boys to back away slowly. A.J. calculates that, with their lack of food and increased heart rates, they will only have eleven hours to live, but Timmy tells his friends not to panic and to simply imagine how hard of a time the girls are having.
From a cliff above, Timmy's mom calls down to him and says that the wildlife are helping the girls reach the top. They ride on some deer up the cliff side, while Tootie promises to meet Timmy at the top of the mountain, if he survives. Mr. Turner flies overhead and tells Timmy he found a shortcut through a nearby cave, but he collides into a tree and is sent flying away again. Timmy and his friends run into the cave, but are quickly chased out of it by a bear. Meanwhile, the Cream Puffs receive gifts from the woodland creatures: One of them gets an mp3 player, Tootie gets a waffle maker and Mrs. Turner gets a giant diamond ring. Timmy manages to scale the side of the cliff using some rope and the bears tooth that was left in his head. He and the other Squirrel Scouts watch the Cream Puffs get gifts and free rides in envy, Chester wants to join the Cream Puffs just so he can eat the deer, but Timmy says they would never accept a boy into their ranks. Just then though, Sanjay passes by them dressed like a Cream Puff and riding on the deer with them.
Cosmo and Wanda appear next to Timmy and explain their absence was caused by being regurgitated by the mother bird that ate them into her babies' mouths. Wanda says that they are here to help now though, however they promptly caught and swallowed by a frog, causing Poof to start crying. This causes a thunderstorm, and a lightning strike blows Timmy and his friends away. The Cream Puffs have sought refuge in a cave, but their animal friends' singing is reverberating off the walls, and they are braiding poisonous berries into the Cream Puff's hair. Mrs. Turner tries to refuse a massage from a moose, but it keeps stomping on her back anyways. Outside, the storm has cleared up, so Timmy and his friends continue on their way hoping to not run into any more trouble. They encounter a scary looking statue, but on closer look it is a statue of Timmy's dad made out of nuts. Mr. Turner reunites with them and explains that after crashing into a cliff, the squirrels nurtured him back to health, and built the statue of him since he has become their leader. Mr. Turner accidentally tells the squirrels to fly Chester off to be sacrificed in squirrel talk, before correcting himself and giving the proper command for the squirrels to take him and the other scouts up to the top of the mountain.
The Cream Puffs are now being chased by the woodland animals, who are still singing. Once it is seemingly over. They begin singing again, but this time they sing their song more and more loudly than than ever. Mrs. Turner finally snaps on the animals, saying that they are annoying and they smell and she hates what they did to her hair, but this causes the animals to turn on the girls and chase them back down the mountain. Overhead, Timmy spots the girls are in trouble and directs his father to have the squirrels save them, and to forget about the bet. The flying squirrels save the Cream Puffs, who then fly both groups to the top of the mountain before dropping them after A.J. points out squirrels cannot carry that much weight. The group pummels toward the summit of the mountain and lands in a pool. It turns out the top of the mountain was actually a resort spa.
Later, The Cream Puffs and Squirrel Scouts are playing in the pool while Timmy's parents relax nearby. Cosmo says that he worked up an appetite after the long slow passage out of the frog that ate him, but he and Wanda are suddenly caught while in goldfish form in a fish net by Chester who wants to cook and eat them. Mr. Turner tells his wife that they should never make a foolish bet like that again, while Mrs. Turner is relieved the woodland critters are gone. However, the animals show up again in the bush behind Timmy's parents, so Mr. Turner quickly makes a bet that he can reach the bottom of the mountain first. Mrs. Turner accepts the challenge again by slapping her husband with her glove, and the two are chased down the side of the mountain by the angry woodland animals while also screaming out "WHY DOES NATURE HATE US?".