Four years have passed since the catastrophic incident at Lockwood Estate and the volcanic eruption on Isla Nublar. Now, de-extinct dinosaurs roam the planet unchecked, leading to significant ecological turmoil and perilous encounters for humanity. In the midst of global efforts to regulate these invasive species, Biosyn Genetics has set up a dinosaur sanctuary nestled in the stunning Dolomite Mountains of Italy. Here, they engage in groundbreaking Genomics research, claiming to explore revolutionary pharmacological and agricultural advancements. This monopoly over dinosaur research has seen the company’s profits skyrocket.
Meanwhile, Claire Dearing (Bryce Dallas Howard), the former manager of Jurassic World and a passionate advocate for dinosaur welfare, alongside Zia Rodriguez (Daniella Pineda) and Franklin Webb (Justice Smith), is still deeply involved with the Dinosaur Protection Group. They dedicate themselves to uncovering illegal breeding operations while Owen Grady (Chris Pratt), a former Jurassic World employee and remarkable Velociraptor trainer, has taken on the role of a dinosaur wrangler, working to relocate lost dinosaurs.
At their secluded cabin in the Sierra Nevada Mountains, Claire and Owen are also caring for Maisie Lockwood (Isabella Sermon), a 14-year-old girl cloned from the DNA of Benjamin Lockwood's daughter. They safeguard her from unscrupulous genetic research firms eager to exploit her unique DNA for dubious purposes.
However, their tranquil life is shattered when Owen's trained Velociraptor, Blue, suddenly arrives with an asexually-created hatchling, which Maisie affectionately names Beta. Feeling increasingly stifled by her secluded existence, Maisie ventures out, inadvertently drawing the attention of Biosyn operatives who kidnap her and capture Beta.
Simultaneously, an alarming resurgence of giant locusts, believed to have been extinct, wreaks havoc on crops across the globe. Dr. Ellie Sattler (Laura Dern), a paleobotanist and one of the original Jurassic Park consultants, discovers a troubling trend—locally generated crops cultivated with Biosyn seeds are untouched. This leads her to suspect that Biosyn may be behind the locust outbreak. Seeking assistance, Ellie turns to her former partner, Dr. Alan Grant (Sam Neill), a renowned paleontologist. She persuades him to join her in infiltrating the Biosyn facility to collect a DNA sample to substantiate her theory.
Panic ensues as Claire reaches out to Franklin for aid. Now working with the CIA's dinosaur unit, he deduces that Maisie and Beta have likely been taken to Malta. Upon arriving, Claire and Owen navigate through a bustling black market for dinosaurs, where they hope to locate the kidnapper, Rainn Delacourt (Scott Haze). When law enforcement mounts a raid, Delacourt retaliates by unleashing predatory dinosaurs, creating chaos. In the ensuing mayhem, Delacourt meets his demise, revealing he was under the orders of Soyona Santos (Dichen Lachman), who poses a new threat for the group.
With the help of Barry Sembène (Omar Sy), a former animal trainer at Jurassic World now turned French Intelligence agent, Claire and Owen learn that Maisie and Beta are en route to Biosyn’s remote Italian research site. They enlist the aid of Kayla Watts (DeWanda Wise), a cargo pilot with a heart, who lifts them to the facility. There, Dr. Ian Malcolm (Jeff Goldblum), a now-conflicted chaos theorist and former Biosyn consultant, seeks Ellie’s help to expose illegal activities orchestrated by CEO Dr. Lewis Dodgson (Campbell Scott), who has been tipped off by Ramsay Cole (Mamoudou Athie).
The plot thickens as Dr. Henry Wu (BD Wong), the original geneticist behind the Jurassic operations, reveals the depth of the conspiracy—he engineered the locusts as a means of control over the world's agricultural output. Despite his initial allegiance to Dodgson, he now wishes to eliminate the swarms to prevent global famine.
During this chaotic narrative, Maisie manages to escape her captors alongside Beta. An altercation ensues as a Quetzalcoatlus attacks Kayla's aircraft within Biosyn’s air corridor, leading to a crash that splits Owen, Claire, and Kayla apart. After a series of encounters with fearsome dinosaurs, the trio reassembles within the Biosyn facility where Ellie and Alan have been busy collecting evidential samples.
However, the corrupt Dodgson learns of their breach and resorts to desperate measures, incinerating evidence of his wrongdoing, which results in a fire and a frantic evacuation. As the tension mounts, alliances are tested within the high-pressure setting of the rooms filled with threats both human and prehistoric.
In an explosive climax, the group manages to escape and has a heart-pounding confrontation with terrifying creatures, including a Giganotosaurus and a deadly Therizinosaurus. The climax reaches its peak when the rogue elements within Biosyn face their inevitable reckoning—Dodgson's fate sealed by the very dinosaurs he pursued for profit.
Ultimately, with the authorities alerted, allies unite against the greater threat of Biosyn’s remnants. The film closes with an attempt at balance as the escaped dinosaurs head toward a sanctuary while Wu accelerates his pathogen development to neutralize the locusts. As the world grapples with its new reality, dinosaurs and humans are now inexorably intertwined in a delicate equilibrium, all while the United Nations designates Biosyn Valley as a protected area for dinosaur coexistence.
