Right after the events of the film The Black Demon, El Rey is recruited once more by an aging cyborg Bella and Mateo, who has learned how to summon another divine weapon that can defeat the shark. They head to the Revillagigedo Islands, where the Black Demon is attacking wealthy tourists, and call up Zipacna, a 70-foot-long prehistoric crocodile. When the two titans clash, our world is irrevocably changed. Which kaiju will emerge victorious? And are they the only two giant denizens of the dark?