The story starts from a place where researchers from outside the planet are experimenting with a type of material and testing it on mice that do not go well and all but one person is killed. The only survivor of this test when transferring these chemicals is facing a problem that causes all specimens to reach Earth from outside the atmosphere, and when they encounter these specimens to animals, they convert them to massive animals.
Davis, a primatologist, works in a zoo and has a very good relationship with animals, especially a gorilla called George. But during the fall of the infected viruses, George also becomes infected and becomes a gigantic giant, which is very wild and attacks humans. Because Davis is interested in this gorilla, instead of killing him, he decides to help him, but Chicago is almost extinct and he must quickly find a solution to the problem.