__________________ "Happiness is a lie. Life is horror. The light is always dying all across the universe. The last star will flicker out someday, when it does, all that remains is shadow. And I will be its king!"'-Amahl Farouk
[SPOILER - highlight to read]: : : The Monarch organization locates Mothra using the Orca, a device developed by Dr. Emma Russell (Vera Farmiga). Terrorists led by Ian Kane (Charles Dance) attack the base and capture Emma and her daughter Madison Russell (Millie Bobby Brown), while Mothra escapes. Emma’s ex-husband Mark Russell (Kyle Chandler) is recruited by Dr. Ichiro Serizawa (Ken Watanabe) and Dr. Vivienne Graham (Sally Hawkins) to help Monarch rescue them. They locate the terrorists in Antarctica and learn that Kane wants to unleash ancient monsters upon the world to restore its balance, and that Emma and Madison are working for him. Emma uses the Orca to awaken Ghidorah and escapes with Madison and Kane.
Kane and his followers go to Mexico to awaken Rodan. Godzilla intervenes, but is ambushed by Ghidorah and mortally wounded by the Oxygen Destroyer, an experimental weapon developed by the United States military. Ghidorah awakens more monsters around the world (some OCs, some old like Anguirus, some cryptids like Nessie) and goes on a rampage, leading Madison to realize it was a mistake to awaken him. While the military attempt to fight the monsters, Monarch finds Godzilla in an underwater temple in an ancient city and learn he is still alive. Serizawa sacrifices himself to detonate a nuclear weapon near Godzilla, who absorbs the radiation and regains his powers.
Madison uses the Orca to lure the monsters to Boston, where Kane and his followers are hiding, in hopes that one of them can kill Ghidorah. Emma leaves to rescue her while Kane and his followers escape. The monsters arrive. Mothra fights and severely injures Rodan before being killed by Ghidorah, who is then confronted by Godzilla. Emma sacrifices herself to use the Orca to distract Ghidorah long enough for Godzilla to kill him by melting him with atomic pulses, ripping off Ghidorah heads, starting to eat it, and melting it with an atomic breath as the head tries to slither out of his mouth. Mark reunites with Madison, while Godzilla becomes the “king of the monsters”, and the others bow to him.
In an after-credits scene, Kane returns to Mexico to retrieve a Destroyah crab found by a fisherman.