Little Bear's Adventures of The SpongeBob SquarePants Movie is an upcoming Little Bear/Paramount crossover to be made by Hiatt Grey.
A group of pirates find tickets to watch The SpongeBob Movie in a treasure chest and enthusiastically sing the SpongeBob SquarePants theme song, enter a movie theater, raid it and sit down to watch the movie.
The film opens with SpongeBob Squarepants dreaming about managing the Krusty Krab restaurant and saving the day during a crisis. He wakes up and cheerfully prepares for the opening ceremony for The Krusty Krab 2, expecting his boss Mr. Krabs to promote him to manager of the new restaurant. However, Krabs instead names Squidward Tentacles manager, believing SpongeBob is too immature to handle the role.
That night, SpongeBob goes to his favorite restaurant, Goofy Goober's, where drowns his sorrows in ice cream with his best friend Patrick Star. Elsewhere, Mr. Krabs' business rival Plankton steals King Neptune's crown, leaving evidence false evidence to frame Mr. Krabs for the crime, and sends the crown to Shell City, a distant, mysterious land from which no fish has returned. The next morning, Neptune barges into the Krusty Krab 2 and threatens Mr. Krabs for his alleged thievery. SpongeBob later arrives and chastises Krabs under the influence of an ice cream headache, but seeing his boss's life is at risk, he promises Neptune that he will retrieve the crown from Shell City. Neptune freezes Krabs and orders SpongeBob to return with the crown in six days for him to spare Krabs' life. Neptune's sympathetic daughter, Princess Mindy, gives Spongebob a Bag of Winds so that they can return from Shell City once they find the crown. SpongeBob and Patrick leave for Shell City in the Patty Wagon, a car shaped like a Krabby Patty.
After Spongebob and Patrick leave, Plankton steals the Krabby Patty formula and uses it to produce and sell Krabby Patties at his restaurant, the Chum Bucket, claiming that Krabs bequeathed him the recipe. As a contingency, he hires a hitman named Dennis to eliminate SpongeBob and Patrick. Squidward discovers the truth about Plankton stealing Neptune's crown and tries to alert Neptune. However, Plankton uses mind-controlling bucket helmets, disguised as souvenirs, to control Bikini Bottom's residents, including Squidward, and renames the city Planktopolis.
As their journey continues, SpongeBob and Patrick reach a dangerous trench, but Mindy helps them past it by making them think she can turn them into men. They are stopped by Dennis, who tries to crush them with his spiked boots, but he is in turn stepped on by a seemingly massive hardhat diver they believe to be a Cyclops. The diver grabs SpongeBob and Patrick, and takes them to his beachside store, revealed to be Shell City. At the store, SpongeBob and Patrick find the crown, but are nearly killed when the diver attempts to dry them out using a heat lamp. Their tears short-circuit the lamp's power cord, and its smoke activates the sprinkler system, reviving their bodies and the other dried sea creatures intended to be sold as souvenirs. As the sea creatures attack the diver, SpongeBob and Patrick take the crown and head for the beach. Patrick inadvertently loses the Bag of Winds while attempting to use it, but David Hasselhoff appears and offers them a ride; Dennis catches up to them but is knocked by a catamaran back into the sea.
At the Krusty Krab 2, King Neptune arrives to execute Mr. Krabs. SpongeBob and Patrick return with the crown just in time and confront Plankton, who drops a mind-control bucket on Neptune, enslaving him. SpongeBob performs the song "Goofy Goober Rock" and transforms into an electric guitar-wielding wizard, freeing Neptune and Bikini Bottom's residents during of the song. Plankton is arrested, and Neptune thanks SpongeBob for his bravery and thaws Mr. Krabs, who makes SpongeBob manager of the Krusty Krab 2 in gratitude.
A post-credits scene shows a theater usher telling the pirates to leave the theater so she can clean up the mess they left, to which the pirates reluctantly agree.