As Mr. Krabs gets ready to celebrate the Krusty Krab's eleventy-seventh anniversary, SpongeBob, Patrick, and Squidward accidentally lock themselves in the freezer and put the whole party in jeopardy.
SpongeBob's pet, Gary, mysteriously begins to bite the residents of Bikini Bottom, and when word spreads that he has a rare disease called Mad Snail Disease, which turns those who get infected into zombies, SpongeBob runs to the Krusty Krab.