Christopher Robin's mother orders him to clean up his messy room. To cut the work in half, he, Pooh, Piglet and Tigger throw everything under the bed. But, when that happens, the bed becomes another land, ruled by the evil Crud. Pooh and Piglet investigate and are kidnapped by Christopher Robin's crayons. Later, Tigger and Christopher Robin follow after them and meet Crud. Crud tells Christopher Robin that the whole "Under-the-Bed" is all made out of stuff he threw under the bed. He's also making a plan to release Christopher Robin's vacuum in reverse, making the world get covered by dirt. Tigger is also kidnapped and Christopher Robin imprisoned. Piglet, attempting to clean up the cell floor, discovers that the floor is dirt and by cleaning it, it makes an escape hatch. Pooh, Piglet and Tigger then disguise as a crayon and rescue Christopher Robin. When they make a break for it, they meet up with Crud and what was once his minions have teamed up with Christopher Robin to clean up the crud. After the adventure, Christopher Robin promises to always clean up his room. Then his mother is proud of him that his room looks clean as a whistle, then she was about to put on sock under the bed, but Christopher reminds her that it needs to go into the laundry basket, his mom wonders if Christopher can go outside and play, but Christopher reminds her that he has to take a bath first.
The title is based on the catchphrase: "Cleanliness is next to godliness."
In the opening scene, Christopher Robin, Pooh, Piglet and Tigger have a fantasy sequence in which they are being chased by a tornado (later revealed to be a fan). The backgrounds are painted to look like the sepia-toned Kansas from the 1939 classic The Wizard of Oz, with A. Arnold Gillespie's muslin sock tornado that sends Dorothy and Toto to the land of Oz, given a personification.