While he was looking for spare change as usual in his cheap ways, Mr. Krabs noticed an over-sized soy bean near Sandy's treedome. Interested in what could have enlarged the plant, he asked Sandy a tour of her residence. Sandy revealed the growth serum that made the plant enlarged, prompting Krabs to steal it out of sight. Vacating the dome and entering the Krusty Krab, he called SpongeBob for a Krabby Patty to test the growth serum and found that it worked. The experiment, to Krabs's satisfied impression, worked, guaranteeing another money-making scheme. However, the patty kept growing until havoc started.
Mr. Krabs still thinking it would make him rich, tried to keep SpongeBob and Squidward at the Krusty Krab to work until Mr. Krabs sees the cash register getting buried by it. He then runs to save it but is then swallowed up as well. SpongeBob and Squidward then ran away as the Krabby Patty devours the whole Krusty Krab completely. In the Chum Bucket, Plankton sees it, and thinking that it was the biggest Krabby Patty that has ever seen runs to it. SpongeBob tries to warn him that he has to get away from the patty, but he never listens, gettng swallowed up as well. Now expanding to a colossal scale, it began consuming Bikini Bottom.
SpongeBob runs hoping to find a solution at Sandy's house, finds her treedome destroyed. Sandy calls to him from her helicopter, and she reveals that the only way to reverse the extending process was if SpongeBob got direct contact with the big patty. SpongeBob complied and absorbed the giant mass of meat into his absorbent body. Everything was back to normal except for SpongeBob in Krabby Patty form and huge. The Krabby Patties which were absorbed were added as Pre-Absorbed Patties in the Krusty Krab. The episode ends with Mr. Krabs selling rare absorbed Krabby Patties at the Krusty Krab while SpongeBob makes it with his thumb from the Krabby Patty, because he was elongated with absorbed meat.