In the year 2055, the Chicago-based Time Safari company provides the affluent elite with an extraordinary opportunity: to experience the thrill of hunting dinosaurs in the past through cutting-edge time travel technology. To mitigate the risks of altering history, this innovative company targets only those dinosaurs destined to die from natural causes and enforces strict regulations to keep clients on their designated paths. However, Sonia Rand, the brains behind the time machine software known as "TAMI," is deeply troubled by the potential repercussions of their operations. Feeling overshadowed and underappreciated, she voices her concerns about clients possibly tampering with history.
During one expedition with clients Eckels and Middleton, chaos ensues when team leader Travis Ryer encounters a malfunction with his weapon. In a harrowing moment, an Allosaurus charges at their group, scattering clients around in a frantic bid for safety. Though Ryer manages to eliminate the dinosaur and safely return to 2055, he remains unaware that one client has unknowingly strayed off the sanctioned path. The following day, reports flood in about alarming shifts in global temperature and humidity, while Ryer observes remarkable changes in plant life.
On their next journey, Ryer and a new group discover that the Allosaurus they intended to hunt is already deceased, coinciding with a volcanic eruption occurring prematurely. This anomaly prompts the government to halt Time Safari's operations pending an investigation. When Ryer consults Rand, he uncovers that Chicago is experiencing "time waves," causing unsettling transformations throughout the city—effects of previous expeditions gone awry. A harrowing encounter at Rand's apartment, where time waves unleash swarms of beetles and uproot trees, reveals the gravity of their situation. Rand warns Ryer that more catastrophic time waves are inevitable, with humans being the final victims.
Determined to rectify the chaos, Ryer and Rand return to Time Safari, enlisting the help of government officials. Ryer resolves to reverse their misdeeds by navigating back in time to lead their previous group back to safety. However, his journey is thwarted as he unexpectedly lands in a desert, barely dodging a stampede of mounted warriors. Panicking, he rushes back through the portal, only to find Chicago overrun with dense foliage and stripped of power. Upon examining the machine’s logs, they discover that Eckels’ previous excursion registered them as slightly heavier, revealing discrepancies when Hatton and Derris opted to disable the bio-filter to cut costs. Rand uncovers that time waves are forming barriers that hinder travel, complicating their efforts to regain control.
In an attempt to patch the fallout from their earlier trip, they deploy the time machine to go back and intercept their past selves. The operations of Time Safari seem unaffected, but they face numerous perils as they navigate a new landscape teeming with lethal hybrids. After rescuing two civilians, they locate Eckels, who assures he stayed on the path. He directs them to find Middleton, but by the time they arrive, Middleton has succumbed to the toxic forces of the new ecosystem and tragically takes his own life. The expedition uncovers a significant clue—an extinct butterfly preserved on Middleton’s shoe—highlighting the critical nature of their previous actions.
As they rush back to Time Safari amidst further time wave incursions, they find Hatton dead and the time machine inoperable, submerged beneath water. Rand manages to secure the hard drive containing TAMI. She devises a plan to utilize a nearby university's particle accelerator as a makeshift time machine. Derris’ fate intertwines with the chaos as he meets a grim end at the hands of ferocious gorilla-bat hybrids.
With only Ryer and Rand emerging as survivors, they reach the university just in time. Rand recognizes that with the emergence of horrifying Baboonlizards signals human extinction on the horizon. Preparing the accelerator, she bravely stays behind while Ryer ventures through the time portal, narrowly escaping the last wave that transforms Rand into a grotesque humanoid catfish creature. Ryer reunites with his former expedition team and urgently relays the devastating truth about the bio-filter being deactivated. He intervenes just in time to prevent Middleton from stepping off the path, thus resetting the timeline.
The expedition successfully returns to their original time, with Jenny acknowledging the fix concerning the bio-filter. In a moment of bittersweet clarity, she shares that she encountered a version of Ryer from the previous timeline. After reviewing the footage, Ryer shares his discovery with Rand, realizing that the grim prophecies she foretold have indeed come to fruition. Together, they seemingly work to dismantle Time Safari, vowing to prevent such disasters from repeating in the future.
