In the closing days of 2015, humanity discovers that they are not the dominant species. When a nuclear test unwittingly disturbs Giant Animals called "Kaiju," who are divided into factions: Guardians, Neutrals, Rouges, Extraterrestrials and Renegades. Big Boy, a Dinosaur-like Guardian Kaiju, embarks on what is initially a self-defensive rampage against the humans, however, when another threat from ancient times looms, he and his fellow Guardians must begin to protect Earth. They are aided by the Kaiju Research Organization Fathom, while the Kaiju are also hunted by Fathom's rouge splinter organization Hunter Force.
