Sandy toll you, SpongeBob and Patrick being given the task of pet-sitting Sandy's pets while she is out of town. One of the many animals left in their care is a small Monarch caterpillar named Wormy. Despite her requiring the least attention, SpongeBob and Patrick quickly befriend the caterpillar and enjoy a day of play together. As the two leave, they vow to have even more fun with Wormy the next day but you decide to stay for the night Overnight, Wormy undergoes a quick metamorphosis and becomes a monarch butterfly. When they return the following morning, SpongeBob and Patrick search for their new friend, but merely see what looks like a beautiful winged creature instead. Upon opening the jar and finding only Wormy's discarded chrysalis and best friend ribbon inside, Wormy flies onto SpongeBob's helmet who gets a close up of a frightening bug. SpongeBob and Patrick scream in horror as they come to the grim conclusion that this "horrific beast" has devoured Wormy and is now on the loose. They try to trap the supposed monster by disguising Patrick as bait. When this fails after Patrick sees it up close, SpongeBob manages to encase the butterfly in a bubble and releases her outside the treedome, in an attempt to "save" Sandy's pets. However, now the butterfly is loose in Bikini Bottom, so SpongeBob and Patrick chase after her. Beating the creature to the Krusty Krab, SpongeBob interrupts Squidward's photoshoot of Mr. Krabs with the very first dollar he earned at the Krusty Krab, so he could warn Mr. Krabs and Squidward, both of whom scoff at the insect human. Squidward and Mr. Krabs have a look and they both laugh until they sees the butterfly's scary close-up. Upon seeing this, they both scream in terror as their teeth and eyes fall out. The two are scared senseless and run away, leaving their discarded undergarments behind. This causes SpongeBob and Patrick to believe that they were also eaten. SpongeBob and Patrick begin to spread news of the "terrible monster" throughout Bikini Bottom. Mass chaos erupts with every tiny flap of her wings, and as a result of the people's hysteria, the whole town ends up destroyed in a fire, you are the last survivor as everyone is gone except for her