Nicole, Granny Jojo, Richard, and Anais are taking a trip to a hotel, so they leave. Gumball and Darwin have to take care of Granny Jojo's pets. Their favorite one is a slime named kenneth. They play with him for a long time. They do not want the day to end, because they want to play more with Kenneth. Gumball gives him a 'best friend ribbon' and he and Darwin promise to come out the next morning.
Overnight, Kenneth turns into a monstrous beast. The following day, Gumball and Darwin see there is a mouse tail. They let him go, and then concluded that he must have eaten the mouse). They start panicking and set up traps, but they do not work, until Gumball finds a huge bubble maker to trap Kenneth. It goes out of the Watterson's house and heads towards the Elmore Hotel, where a hotel employee is about to take a picture of The Wattersons with there first dollar as their last one was gone since they bought an expensive car. Gumball and Darwin go through the 'secret entrance', and hide inside the Watterson's new car. They tell them about the 'monster', but the Wattersons think it is harmless. They look closer, and see a frightening roaring creature (an extreme close-up of Hedorah from Godzilla), and get eaten. Gumball and Darwin see that Kenneth has eaten them, and warn Elmore. It is only then that the destruction starts, with a conflagration similar to The Great Fire of London. It is not until the military take down/kill the beast that the terror/tragedy ends. After that the trapped victims thank Gumball, Darwin and the military for saving them but Granny Jojo was nowhere to be seen as she was already digested as told by Nicole then a funeral was for her as a piece of slime was buried a new monster was created a slimy, roaring and buzzing horse fly called Kenneth II.