Daggett gets taken in by EC comics books' "The Konspiracy Komiks Presents: The Attack of the Howler Leeches" and sends away for the Konspiracy Kevin head doll. When Dag pulls the string, the head warns him that all animals will be attacked by the Alien Howler Leeches. He panics while Norbert thinks he's been scammed. Dag persists in his paranoia, so Norb recruits Big Rabbit, Barry the Bear, and Truckie to justify his fears.

The Beavers' dam is haunted, and they like it that way, having fun with their ghostly visitors. Unfortunately, our goofy scientists are now paranormal researchers and in their typical blind way act on the assumption that all ghosts are bad.

Strange things happen to the beaver brothers' forest friends when Norb gives Dag an organizer in which to list those who have wronged him.

An old home movie confirms Norb's suspicions that Dagg isn't his real brother. Soon, Norb is "reunited" with his brother Byron (who looks like a super-smart Norbert), while Dagg gets stuck with Byron's "brother" Randy (an incredibly stupid version of Dagget). But Norb grows tired of being the "dumb one" compared to Byron, and begins to wonder about the real meaning of brotherhood.

Dagget and Norbert get tired of having to live together in the same room, so they decide to make their own rooms. The construction process soon turns into a frantic show of one-upmanship, with each beaver brother trying to make his room bigger and fancier.

Dag purchases a white ant farm' and unwittingly releases a colony of termites who slowly devour the dam. As the boys battle the persistent insect invader, Dag's nerve fails and he joins the colony. Norb must save his brother, while also fighting off the termites alone!

After a wizard mistakenly sends a doofy warrior to the Beaver's pond, the boys can't seem to get rid of him or his wielding sword.

A Dr. Seuss type creature appears in the dam to show the boys how to play nice, safe and fair. But he goes too far when he tries to make Dag's environment perfectly nice, safe and fair by removing his brother Norb.

Everyone, especially Norb, is relieved when Dag decides to mimic his comic book hero Muscular Beaver and go into disillusioned retirement. His retirement is short-lived when he discovers that all along Norb has secretly enjoyed dressing up as his nemesis Baron Bad Beaver. The boys must fight one more super battle to end all super battles.

When the dam accidentally falls on Norb's head he develops damnesia and forgets who he is. Trying to restore his memory, Dag shows him old home videos. Norb is so shocked by how badly he used to treat his brother that he resolves not to become himself again, but instead become the always nice brother named Troy.

A raging volnado' (half volcano, half tornado) capsizes the Beavers dam during a party. Everyone escapes but Dag and Truckee. Handcuffed together, the two antagonists must escape from the sinking upside down dam. Meanwhile, Norb and the rest of the gang party in the volnado shelter not missing Dag or Truckee at all.