The program opens with a Ninja Turtles short called Chrome Alone 2: Lost in New Jersey, a cheeky prelude that follows the Teenage Mutant Ninja Turtles as they search for the perfect Christmas gift for Splinter. The quartet discovers knock-off toys based on their adventures, made by a Jersey-based company controlled by a villain named Chrome Dome, an AI robot determined to cash in on their fame. The Turtles quickly realize Chrome Dome can copy their every move, turning their own tricks against them. To outsmart the AI, they stage a clever ruse, coaxing Chrome Dome into mimicking maneuvers that backfire on him. The plan culminates when Leo retracts his limbs into his shell, a move Chrome Dome imitates in a way that makes the robot collide with his own power and explode the factory. With the threat neutralized, the Turtles head home to pick out something heartfelt for Splinter, only to discover that the gifts are disappointing knock-off dolls. In the end, they decide to burn the toy fakes and, in a lighthearted close, Raphael declares that AI isn’t something to celebrate—“AI sucks.”
The main feature, SpongeBob, opens with a legend-style setup. A pirate detail—The Flying Dutchman [Mark Hamill]—tells a story about a cursed pirate doomed to wander the seas until he can find an innocent soul to break the spell. In Bikini Bottom, SpongeBob [Tom Kenny] wakes to a silly revelation: his snail Gary has somehow grown to be “36 clams tall,” a boast that makes him feel like a true big guy. He rushes to share the news with his best friend Patrick [Bill Fagerbakke], hoping they can ride the notorious Shipwreck roller coaster at Booty Beard’s amusement park.
The mood shifts as Mr. Krabs [Clancy Brown] isn’t there to join the adventure, so Patrick helps talk SpongeBob into visiting the Krusty Krab instead. Mr. Krabs shares stories of his own swashbuckling days, recalling a past life as a pirate captain who once sailed with The Flying Dutchman, until he parted ways with a prized horn. Inspired, SpongeBob longs to prove his own bravery and, in a basement moment at the Krusty Krab, stumbles upon a hidden room devoted to the pirate lifestyle. There, he finds the horn of The Dutchman, and, convinced it will make him brave, he blows into it. The horn summons the pirate ship and The Dutchman’s first mate, Barb [Regina Hall], landing in Bikini Bottom. SpongeBob invites himself aboard, with Patrick tagging along, much to their hosts’ annoyance. Mr. Krabs, joined by Squidward [Rodger Bumpass] and Gary, races downstairs but is too late to stop the duo from being swept into a portal that plunges them into The Underworld.
In Challenge Cove within The Underworld, SpongeBob and the ghost crew face a gauntlet of trials designed to test intestinal fortitude, though the point is less about guts and more about proving worth to the curse bearer. Skeleton fish pirates attack as the ghosts fight back, and the group improvises with seaweed “intestines” to outwit their foes, turning danger into a farcical victory when the skeletons laugh so hard they fall apart. Back on the surface, Mr. Krabs, Squidward, and Gary navigate toward the entrance to The Underworld via Bikini Bottom High School, inspired by Davy Jones’s Locker, while SpongeBob and the Dutchman’s crew press on.
The challenges intensify as The Dutchman tries to mold SpongeBob into a true swashbuckler, asking him to let go of a few carefree joys—like blowing bubbles with Patrick—that threaten the curse’s hold. Barb grows increasingly unsettled, realizing that The Dutchman does not value her friendship the way she values his. Along the journey, the squadiel of sirens appears, tugging at the crew with their hypnotic calls; even Squidward succumbs to the allure of their music when Mr. Krabs lunges to pull him away, saving him from danger.
After a climactic sequence of trials, the ghost captain brings them to a final platform where he urges SpongeBob to blow the horn again. Just in time, Mr. Krabs, Squidward, and Gary interrupt, forcing a confrontation about the truth of the Dutchman’s past. The revelation shocks SpongeBob: Mr. Krabs wasn’t a captain at all, but once served as a fry cook who coveted the horn and stole it from The Dutchman, an act that defined his past missteps. The truth fractures the Dutchman’s hold, and SpongeBob, moved by courage and trust, blows the horn to prove his bravery. In a flash, the two exchange fates—SpongeBob becomes a ghost pirate, “FlyingBob DutchPants,” while The Dutchman becomes human again—along with a jolt that sends Mr. Krabs into a ghostly captain’s life as well. Barb’s heartbreak over losing her captain is palpable as The Dutchman ascends to the surface world, leaving her behind.
Sensing danger and a chance to restore balance, Barb urges the crew to act before sundown: destroy The Dutchman’s horn. SpongeBob and Mr. Krabs retreat to surface Bikini Bottom with the horn still in their grasp, racing the clock to end the curse. The roller coaster at the amusement park becomes a dramatic battleground, and SpongeBob finds the courage to ride it, climbing into the sky and then braving the drop. With a bubble shield, he catches the horn, then crafts a bow-and-arrow bubble to pop it. The horn shatters, and The Dutchman reverts to his ghostly form while his crew turns against him for abandoning them. Barb seizes the helm, seizes the moment, and takes control of the ship, laughing at the turn of fortune.
Back home in Bikini Bottom, SpongeBob and Mr. Krabs return to the ordinary world, grateful for a renewed sense of bravery and purpose. They share a warm group hug with the rest of the Krusty Krab crew and friends, from Patrick to Sandy to Mrs. Puff, celebrating their return to normalcy and the strength found in facing fear together. The day ends with a bit of humor and friendship, but the last beat lingers on a missing piece—Squidward, left behind in The Underworld, reminding everyone that bravery sometimes comes with a price and that friendship is the kind of treasure worth working to recover.
