Spongebob plays Doom and Sandy and Patrick came to his house telling him to go outside which led to Spongebob ripping her head off. Patrick got out the house to hide and Squidward complained and got killed by Slendybob with a chainsaw.
While Larry is walking in Bikini Bottom, Slendybob appears and chases him, tearing apart his head and killing him. Later in Spongebob's dimension, Spongebob starts sleeping in his house, which Slendybob arrives.
Slendybob arrives at Boating School to kill Mrs. Puff, making her worried, she attempts to hide in the classroom, but Slendybob finds her and laughs in a chair. Mrs. Puff then attacks Slendybob who is holding a knife.
Mrs. Puff wakes up, takes the knife out of her chest, and finds a crowbar somewhere, she then meets Sara Ryder, who tells her she's not much of a player, Mrs. Puff throws her crowbar at Sara and decapitates her before riding away.
We see Incidental 85 who tells us to watch out for Slendybob. Slendybob then arrives in a free ice cream truck, which Incidental 85 then goes to the back of it and gets captured by Slendybob and taken to jail where Mrs. Puff is locked up.
Squilliam walks in his house and hears Slendybob, then the clock tells Squilliam his time is up, which Slendybob then kills him.
Slendybob is shot from behind by Mrs. Puff wand falls off the balcony and into a pool below it, supposedly killing him. After Slendybob's defeat, the town of Bikini Bottom had resettled and built a new community with the help of Mrs. Puff.
Slendybob turns Squidward into a demon, Spongebob and Patrick get scared by him and run out of the house, Slendybob uses his lasso to pull Patrick away to kill him.
After being captured by Sandy, Spongebob is thrown of a plane and lands in hell, where he is chased by Patrick, Spongebob finds Halo armor and wrestles Patrick.
Mrs Puff arrives from a time machine in a snowy machine in a snowy place in an attempt to stop Slendybob, Slendybob shoots snowballs at her which she manages to avoid, she then encounters the demonized Mr. Krabs and Plankton.
Mrs. Puff wakes up, takes the knife out of her chest, and finds a crowbar somewhere, she then meets Sara Ryder, who tells her she's not much of a player, Mrs. Puff throws her crowbar at Sara and decapitates her before riding away.
Doodlebob kills Slendybob by impaling him through the back an out of the mouth with a big pencil, ending his reign of terror. Doodlebob tells a horrified Spongebob "You Spongebob, me Doodle" before running off.