Ten years after the Battle of the Breach, former Jaeger pilot Jake Pentecost (John Boyega) - son of deceased Kaiju War hero Stacker Pentecost - makes a living by stealing and selling Jaeger parts on the black market in the Los Angeles area. Many people want to assemble their own Jaegers and are willing to pay handsomely for it. Power cores sell at a premium as they are very rare, Most of the world has recovered from the Kaiju attacks, but a few coastal cities have not.Jake had already promised a power core to a black-market dealer, but when he reaches the location, he finds the core had already been stolen. Jake tracks part of a disabled Jaeger's power core to the secret workshop of fifteen years old Jaeger enthusiast Amara Namani (Cailee Spaeny). Amara was building her own Jaeger named Scrapper. Scrapper is small enough to be run by a single pilot. Both are arrested by the Pan-Pacific Defense Corps (PPDC) after an altercation with the Jaeger November Ajax. Jake is a repeat offender and was arrested in a rogue Jaeger. Jake's adoptive sister and PPDC General Secretary Mako Mori (Rinko Kikuchi) gives Jake a choice between prison and returning to the PPDC as an instructor with Amara as his recruit.Upon arriving at a Shatterdome in China, Jake starts training Jaeger program cadets with his estranged former co-pilot Nate Lambert (Scott Eastwood). Nate and Mako reveal to him that the Jaeger program is threatened by Shao Corporation's drone program, which offers to mass produce Kaiju-Jaeger hybrid drones developed by Liwen Shao (Jing Tian) and Dr. Newton Geiszler (Charlie Day). Geiszler is the head of research and development for Shao.Hermann Gottlieb (Burn Gorman), is a scientist and officer who stayed and continued to work in PPDC with Mako. Hermann believes that it takes too long to deploy Jaegers in battle and proposes attacking rocket Thrusters to them (using Kaiju blood as fuel), an idea that Geiszler shoots down. Hermann says that he still gets nightmares about Kaiju's after he and Geiszler drifted with the Kaiju brain.Nate is joined by Jules Reyes (Adria Arjona) to train the cadets. Fellow cadet include Renata Gutierrez (Shyrley Rodriguez), Ou-Yang Jinhai (Wesley Wong), Suresh Khuran (Karan Brar), Viktoriya Malikova (Ivanna Sakhno), Ryoichi Hatayama (Mackenyu), Meilin Gao (Lily Ji), Tahima Shaheen (Rahart Adams), and Ilya Zaslavsky (Levi Meaden). The current military thinking is that pilots make a strong bond when they are young, and that makes them a better drift pilot. Nate and Jake are both vying for Jules's affections.Mako has doubts about Shao's drones as remote systems can be hacked or compromised. Mako is due to deliver a final assessment to determine the authorization of the drones at a PPDC council meeting in Sydney but is killed by rogue Jaeger Obsidian Fury before she can report. Jake and Nate were on point in a Jaeger called Gypsy Avenger to protect Mako, but they fail which also proves the futility of the manned Jaeger program.Her death prompts the PPDC council to authorize the drone program and order their immediate deployment worldwide within the next 48 hours. Moments before her death, Mako transmitted the location of a defunct Jaeger production facility in Siberia. Jake and Nate travel to the area in their own Jaeger, but Obsidian Fury destroys the complex and engages them in battle. Upon destroying its reactor, they find that Obsidian Fury was controlled by a Kaiju's secondary brain, which testing shows was grown on Earth.Amara and the cadets inspect Obsidian Fury. Amara tells Jake that the rogue Jaeger had technology inside made by Shao industries.When the drones reach their respective locations, they are taken over by cloned Kaiju brains and simultaneously attack Shatterdomes worldwide, inflicting heavy casualties on the PPDC forces and incapacitating almost all Jaegers. Hermann Gottlieb seeks out Geiszler for help, only to discover that Geiszler is the mastermind behind the attack. Geiszler's mind has been taken over by the Precursors, the alien race who created the Kaiju, due to his regularly drifting with Kaiju brains.Seeking to destroy the world for the Precursors, Geiszler, now the Precursor Emissary, commands the drone-Kaiju hybrids to open new breaches all over the world. Although Shao is able to destroy the hybrids in time, three powerful Kaiju - Raijin, Hakuja and Shrikethorn - emerge from the breaches and unite in Tokyo. The team realizes that the Precursors' goal is to activate the Ring of Fire by detonating Mount Fuji with the Kaiju's chemically reactive blood, spreading toxic gas into the atmosphere and wiping out all life on Earth, Terraforming the planet for Precursor colonization.The cadets are mobilized while Gottlieb and Shao repair the PPDC's four remaining Jaegers; Gottlieb invents Kaiju-blood-powered rockets, which launch the team to Tokyo. Although the Jaegers initially repel the Kaiju, the Precursor Emissary merges them into one gigantic beast that quickly overpowers the team, killing Suresh, wounding Nate, and leaving Gipsy Avenger the only operational Jaeger.Jake and Amara pilot it against the "Mega Kaiju," with Shao remote piloting Amara's small, single-pilot Jaeger Scrapper aiding them by locating and welding a rocket to "Gipsy's" right hand and sending the larger Jaeger at tremendous speed into the Mega Kaiju, as it approaches Mount Fuji, which kills the creature. Jake and Amara survive by transferring into "Scrapper" prior to the collision. Nate takes the Precursor Emissary Newt into custody.The captive Precursor Emissary threatens that his masters will attack the world over and over again. Jake replies that next time, humanity will be the ones attacking the Precursors.