In Volcano Island, the Wise Old Crab ans his two crabs are using a ritual to summon 9 heroes. However, the evil enemy known as the Mawgu has used an attack to break the ritual. One crab comments that the heroes are lost, but the Wise Old Crab reassures that they are just scattered, not lost.
Just then, Danny and SpongeBob fell from the sky. The former asks the latter where they are and the Wise Old Crab answers that they're far from home. He tells them that he summons them to go to Volcano Island to defeat an ancient enemy, the Mawgu. The latter has created an ooze that will corrupt everything it touches. Fortunately, there is a legend that a group of people, the Chosen Ones, will save them. When SpongeBob asks how he and Danny can save the island, the crab replies that he must find the other chosen ones first and shows them a safe place to camp.
SpongeBob has found Patrick jumping on a plank. He asks him to join him. Afterwards, the three find one of Danny's friends, Tucker, in trouble by two pigeons. They save him and the Wise Old Crab show them where to camp. Then, he tells them of a prophecy about a "Night Girl" and a "Whiny Cephalopod" will be covered in sand. Tucker asks the heroes to look for stuff they can use to build a camp.
Another one of Danny's friends, Sam fights off two monsters with the Peeler Suit. Danny finds her and asks where did she got the suit. Sam replies that she's trying to help Danny's mother making adjustments to it. Danny asks her to join him finding a whiny guy and save the world. Sam hears a sound and they go to where the sound is.
Meanwhile, SpongeBob and Patrick hear a sound. The former thinks it was the latter farting. However, it is Squidward blowing with his clarinet. He is rescued by SpongeBob, something that he is not happy about.
The Wise Old Crab tells a prophecy for a "Three-Headed Boy" will be found by the exile crabs and that he must be rescued. Squidward orders the heroes to find some food because he's starving.
Meanwhile, Timmy, along with Cosmo and Wanda, is shown play music for the green crabs. He can't stop playing because they will get mad at him if he tries to. The heroes rescue Timmy and the latter wishes that the crabs would freeze. He shows them his Jimmy Neutron communicator so that they can communicate with Jimmy. Unfortunately, the batteries aren't there. SpongeBob reassures him that they will find it.
Just then, a crab tells the heroes the news that the Wise Old Crab is captured by the Great Carapace, who is attacking the city. The heroes manage to defeat him and rescue the Wise Old Crab. Because of that action, they are respected by everyone and got the battery for the communicator.
They contact Jimmy to tell him about their adventure in Volcano Island trying to stop the Mawgu from destroying the universe. Luckily, Jimmy has sent Tucker the plans for his device, the Neutron Rip-Zipper, a device that could recover all the energy that the Mawgu has stolen, therefore saving the universe. He orders the heroes to look for the parts.
Just then, the Old Wise Crab brings a news that the "Deep-Sea Squirrel" is in danger and must find her.
In the jewelled trees, Sandy is shown fighting two monsters and defeat them. When she asks what is going on, Patrick keeps on saying about jumping until Sam says that they were in a dimension to save the universe.
By the time they get back to the Wise Old Crab, he tells them that the Queen of the Myrmec tribe has been kidnapped the Florians and their mad king. He orders them to rescue her because they plan to corrupt her with the ooze.
Meanwhile, the queen tries to get the king to fight the influence of the ooze, but to no avail. The heroes rescued her and the queen commented that she should've have believed Shelley all along. It is the Wise Old Crab that she is talking about. Just then, they found a component for the Rip-Zipper.
The queen tells the heroes that the Plant King has built a dam to stop the river flowing to the Florians' village. With that, they can only drink the ooze, turning them corrupt. She tells the heroes that if they distract the king long enough, the queen's commandos can destroy the dam.
The queen's commando bugs carry the heroes to the Plant King, who is giant cabbage. After defeating him, the river washes him back to normal. He tells them to stop the Mawgu and gives them a component for the Rip-Zipper.
Tucker informs the heroes that they have to set up the Rip-Zipper and Jimmy says about taking it close to the top of the volcano. Upon arriving there, they were confronted by the Mawgu. They follow him to the tornado.
Upon going there, Jimmy informs Danny that if he and the heroes lure the Mawgu into the rip, they could seal it up at the same time. In order to do it, Danny has three teams: Sandy, Sam, Timmy, and Patrick will wait for the Mawgu to get close, Tucker has to stay for the switch, and Danny has SpongeBob and Squidward come with him.
Just as the Mawgu is about to attack, Timmy insults him by calling him a wiener and a toy monster. Angered of being called a toy, the Mawgu gets Timmy and the others' attentions. Danny and SpongeBob have beat the Mawgu and seal him away.
Afterwards, the heroes are prepared to go back to their dimensions.