Beanotown has become boring. All Dennis pranks are backfiring and he seems to have lost his awesomeness. Even his faithful hound, Gnasher, seems fed up with him these days. When Dennis hears about the legendary Golden Pea Shooter of Everlasting Fun, it sounds like the only thing that can solve his problems and return his hometown to its former glory. With the help of his cousin, Minnie and Gnasher, Dennis must go on a quest, discovering the mysterious Chamber of Mischief in his bid to find the Golden Pea Shooter, but a series of tricky challenges (and Dennis nemesis, Walter) stand in his way.