All is peaceful in The Hundred Acre Wood until one morning when a loud and thunderous trumpet-like sound wakes the likes of Pooh (voice of JIM CUMMINGS), Tigger (voice of JIM CUMMINGS), Piglet (voice of JOHN FIEDLER) and Roo (voice of NIKITA HOPKINS) from their slumber. Young Roo then tells his mother, Kanga (voice of KATH SOUCIE), that he's heading off with his friends to visit the wise Rabbit (voice of KEN SANSOM) who may know what's happening.
The wise if cantankerous bunny figures the sound must be from the feared heffalump creature that lives in the nearby Heffalump Hollow. None have ever seen one, but they've heard rumors and they only reinforce their fears of what's presumably a mysterious beast. Roo, however, doesn't seem scared and thinks they should try to capture one. The others agree, but decide that Roo is too young to participate.
The next morning, however, as his friends pack up another friend, Eeyore (voice of PETER CULLEN), like their pack mule and start off on their expedition to find and capture a heffalump, little do they know that Roo has already entered the Hollow. It's there that he meets Lumpy (voice of KYLE STANGER), a young and playful heffalump (elephant) and two soon become fast friends, although Roo learns that Lumpy is just as scared of Roo's world as his friends are of the elephants.
Despite Lumpy's mother (voice of BRENDA BLETHYN) calling out for him, the two continue to play, unaware that they'll eventually run into Pooh and the others, creating some brief tense moments between them.