SpongeBob takes leave from Bikini Bottom in order to track down, with Patrick, King Neptune's stolen crown.
After King Neptune's crown is stolen, SpongeBob and Patrick go on a quest in 6 days to retrieve his crown. On the way SpongeBob and Patrick defeat many evildoers using their brains and bronzes. While this is happening someone is taking over Bikini Bottom and SpongeBob and Patrick must defeat this mastermind.
No one is safe in the colourful and once-peaceful underwater town of Bikini Bottom, as the royal crown of the sea's all-powerful deity, King Neptune, has been stolen by a bold and mysterious thief. Wrongfully accused for this hideous crime, the owner of the seabed's most successful burger joint, Mr Krabs, will have no other choice but to entrust his boxy employee and incurable optimist, SpongeBob SquarePants, and his best friend, Patrick Star, with clearing his name--even though he deprived him of a big promotion. But, where should the team of aquatic detectives start? Given an impossible six-day deadline, SpongeBob and Patrick will eventually find themselves venturing in the unforgiving territory of the God-forsaken Shell City--the dark realm of horrible creatures. Will they manage to find it in time?—Nick Riganas
SpongeBob SquarePants enjoys living a carefree life among his friends in Bikini Bottom. But there's danger brewing this time around. King Neptune's prized crown has been stolen and Mr. Krabs has been framed for the crime. With only six days to reclaim the crown, SpongeBob along with best friend Patrick ventures to the treacherous Shell City where the crown is said to be. Meanwhile, the devious Plankton has finally stolen the Krabby Patty recipe and taken over Bikini Bottom. Now SpongeBob must do everything he can to find the crown and save Mr. Krabs from being cooked before it's too late.—Blazer346
There's trouble brewing in Bikini Bottom. Someone has stolen King Neptune's crown, and it looks like Mr. Krabs, SpongeBob's boss, is the culprit. Though he has just been passed over for the promotion of his dreams, SpongeBob stands by his boss, and along with his best pal Patrick, sets out on a treacherous mission to Shell City to reclaim the crown and save Mr. Krabs' life.—Sujit R. Varma
The film starts with a pirate crew, led by Captain Pinty, eagerly awaiting their treasure: tickets to The SpongeBob SquarePants Movie. When they recover it, they sail to the movie theater and sit down at the front row seats to watch the movie.
SpongeBob SquarePants has a dream of becoming the manager of the Krusty Krab restaurant and that the restaurant is in danger because a customer named Phil has no cheese on his Krabby Patty, but SpongeBob comes in in a limo and puts cheese to the Krabby Patty to save the day. SpongeBob wakes up from the dream, and happily gets ready for the "Krusty Krab 2" opening ceremony, with the hope that Mr. Krabs will promote him to general manager of the new restaurant. At the opening ceremony, SpongeBob is denied the title, which is instead given to Squidward Tentacles, due to being "more mature" than SpongeBob and Mr. Krabs thinking that he's "just a kid" and is unable to handle the task.
Severely depressed, SpongeBob heads to his favorite restaurant, Goofy Goober. There, he eats numerous sundaes with his friend Patrick Star, and wakes up the next morning with a hangover. Meanwhile, Plankton, Krabs' business rival, enacts a plot to steal the Krabby Patty secret formula burger with the dreaded "Plan Z". He steals King Neptune's beloved crown (which Neptune claims symbolizes his authority, even though it is obvious he wants to conceal a bald spot lining the entire top of his head), sends it to Shell City, a hazardous location to which no marine life has ever returned from and is guarded by a killer Cyclops, and leaves a note that says "I stole your crown. Signed, Eugene Krabs".
Incensed, Neptune crashes into the Krusty Krab 2 and assaults Krabs. SpongeBob later arrives and bad-mouths Krabs, but, when seeing Krabs' life is at risk, promises Neptune that he will retrieve the crown from Shell City, but Neptune doubts that SpongeBob is capable of that. In the end, though, his compassionate daughter, Mindy, convinces him. He orders SpongeBob to be back with the crown back in exactly ten days, but thanks to Patrick, who seems to overestimate his friend, the time is argued down to six days. So he will not run away, Neptune freezes Krabs with his trident and says that Krabs will fry if SpongeBob does not complete his task. SpongeBob and Patrick then head off for Shell City in a car shaped like a Krabby Patty.
With his rival frozen solid, Plankton steals the Krabby Patty formula with ease. Meanwhile, SpongeBob and Patrick meet two owners of a gas station who make fun of them for no apparent reason. As the duo push on, their car is stolen by a thug.Back in Bikini Bottom, Plankton sells the Krabby Patty and makes a huge fortune, claiming Krabs willed the recipe to him. He also sends a hit-man named Dennis to pursue SpongeBob and Patrick. Meanwhile, SpongeBob and Patrick recover the car, but are forced to get the key from the thug, who is in a night club where anyone who blows a bubble is mauled. They end up blowing countless and are almost caught, but they escape with the key.
Squidward, meanwhile, uncovers the truth about Plankton stealing Neptune's crown and attempts to alert the authorities, but Plankton uses mind-controlling buckets, disguised as restaurant souvenirs, to control the residents of Bikini Bottom, including Squidward, and renames the city Planktopolis.
Meanwhile, SpongeBob and Patrick discover an ice cream stand and buy some, but it is revealed to be a trap created by a frog-fish. The frog-fish attempts to eat them, but they escape by jumping out of the car. The frog-fish eats the car but is eaten by an eel that lives in a trench filled with carnivorous creatures. They have to cross the trench to get to Shell City but are afraid that it's a job for "men"& they are just kids. Before the two admit defeat, knowing that they cannot cross the trench, Mindy appears to give them encouragement by falsely claiming they are men, not kids, by using her "Mermaid Magic" to give them mustaches (strands of seaweed). Singing a song, SpongeBob and Patrick dance their way across the trench with ease & sidestepping all the monsters with sheer luck, only to meet Dennis on the other side.
Dennis was hired by Plankton to eliminate Spongebob & Patrick so that they cannot come back with Neptune's crown. Before Dennis steps on them with his giant boot, he is stomped on by a human boot. The human, revealed to be the Cyclops Mindy warned them about, grabs SpongeBob and Patrick and heads off for his store by the beach, which is in fact "Shell City" itself; (until the duo returns to the Krusty Krab 2, besides the SpongeBob, Patrick, and the sea animals, the film is shot in the real world).
When they arrive, SpongeBob and Patrick find the crown, but encounter a lethal drying-out process which kills them. However, they shed tears that short-circuit the heat lamp, which releases smoke and activates the emergency sprinkler system, reviving them, as well as the other dried-out sea creatures being sold as souvenirs. While the sea creatures attack the Cyclops, including a lobster who sprayed Elmer's glue onto him, SpongeBob and Patrick take the crown out to the beach. After accidentally losing the bag of winds Mindy gave to return to Bikini Bottom, David Hasselhoff offers the two a ride, which they gladly accept.
On the way, Dennis catches up to them, but is struck by a catamaran back into the sea. Back at the Krusty Krab 2, Neptune arrives to execute Krabs, while Plankton eagerly watches. In the nick of time, SpongeBob and Patrick return with the crown, save Krabs, and then confront Plankton. In turn, Plankton drops a mind bucket on Neptune. Just as Plankton thinks he is triumphant and has won, SpongeBob, cherishing the fact he is just a kid yet he accomplished a lot in the past six days, five minutes, and 27-and-a-half seconds, uses his imagination to play the Goofy Goober theme in the form of a rock song (a parody of "I Wanna Rock" by Twisted Sister), using his guitar to free Plankton's slaves. Realizing defeat once again, Plankton tries to escape, but is trampled by Bikini Bottom's citizens.
Plankton is arrested and incarcerated. King Neptune thanks Mindy for her bravery and unfreezes Krabs, who graciously gives the title of general manager of the Krusty Krab 2 to SpongeBob. During the end credits, SpongeBob is seen doing jobs and chores for Mr. Krabs with an oversized Krusty Krab employee hat.In a post-credits scene, a theater usher forces the Captain and his pirate crew to leave.
