After returning home to Hawaii for summer break, Lucy is reunited with her father and their pet chimpanzee Ben. Lucy and her friends decide to throw a pool party to take advantage of an empty house after Lucy's father is called away for work. Unbeknownst to them, Ben is bitten by a rabid animal and the gentle chimpanzee they once knew is no more. The group is forced to barricade themselves in the pool, but with no means of calling for help, they must work together to figure out how to outsmart the now ferocious Ben and survive their ordeal.