Dennis Cooper, a simple and naive peasant, sets out for the town to find his fortune after the death of his father. Upon arriving, he finds himself in the midst of a chaotic town where the citizens are plagued by the terrifying monster known as the Jabberwocky. Despite the danger, Dennis seeks work and ends up employed as a clerk at a tannery run by the greedy and deceitful Mr. Fishfinger.
Dennis soon falls in love with a beautiful and kind-hearted peasant girl named Griselda. Meanwhile, the inept knights of the kingdom are failing to defeat the Jabberwocky. The king and his adviser, the elderly and senile Mr. Bloat, are at a loss for a solution.
As the attacks by the monster become more frequent and destructive, the desperate citizens of the town turn to a superstitious and depraved cult leader named The Cooper, who claims to have the power to defeat the Jabberwocky. In reality, The Cooper is a fraud and his dark rituals only make matters worse.
With Griselda's encouragement and a newfound confidence, Dennis sets out to confront the beast himself. In a hilarious and absurd battle, Dennis defeats the Jabberwocky using unconventional methods and surprising allies.
In the end, Dennis becomes a hero and Griselda agrees to marry him. However, his victory is short-lived as he discovers Mr. Fishfinger's true evil intentions and the corrupt nature of the kingdom's leadership. Dennis realizes that his true adventure is only just beginning.