On the picturesque island of Tian-Huo, a team of scientists is busy examining a dormant volcano. Young Meng Li expresses her concerns to her mother, Sue Miller, stating, "the snow is on fire." Initially dismissing her daughter's words as impossible, Sue soon realizes that Meng is witnessing ash being ejected from the volcano. Within moments, fiery rocks shoot from the volcano like meteors, forcing the researchers at the base camp to evacuate urgently. Sue manages to place Meng on one of the departure trucks but cannot board herself. Her husband, Professor Tao, attempts to reach her in his jeep but meets with a disastrous accident, leaving Sue with a heartbreaking farewell as a hot cloud of gas swells toward her.
Years roll by, and Professor Tao recounts the story of the volcano to his students, emphasizing how it transformed from a state of apparent stillness to erupting within minutes—a stark contrast to other volcanoes like Vesuvius, which offered at least hours of forewarning. Meanwhile, Jack Harris, played by Jason Isaacs, has established a resort and theme park around the volcano, confidently telling visitors that it won't erupt for another 150 years. He markets this thrilling experience to tourists, insisting that they pay a premium to be on the edge of danger, although experts remain skeptical about the volcano's true potential for danger.
Now a grown-up, Meng engages in the critical task of placing measuring instruments across various locations around the volcano. This risky operation sees her being lowered into a precarious hole, and she narrowly avoids a catastrophic fall as she is hoisted back up. Tensions unfold as a romantic subplot develops between two researchers, with the man receiving a ring from the girl's grandfather, reflecting human connections amid the chaos.
As tourists arrive, Jack is excited to greet them, entrusting his wife, Meng Li, to guide a group around the resort. However, Meng quickly makes it known to Jack that she desires more attention from him. Just then, Tao arrives on the island to escort Meng away, now convinced after watching footage of the volcano that it poses an imminent threat. Nevertheless, Meng is determined to stay and presents her father with a model of the volcano that showcases real-time readings from her equipment.
The adventure escalates as the tour group boards a monorail to explore the crater, lulled into a sense of safety, and they descend in a specially designed vehicle meant to resist volcanic heat. They are treated to stunning views from an observation platform. However, the cheerful outing takes a drastic turn when the couple goes swimming, only to discover their exit route has been sealed off by encroaching lava.
As Meng and Tao maintain lines of communication with the base, they alert the tourists of impending danger, and just as predicted, the volcano awakens. Chaos ensues as one researcher tragically falls to his doom, and several tourists are caught in the eruption's wake. The tour group barely escapes with their lives as their vehicle is obliterated. Although they entered on one cable car, their escape demands the use of both cars; with Meng teaching someone to operate one of the cars, she, Tao, and Mrs. Harris find themselves in a predicament when one of the cables snaps. The desperate tourists must leap from one car to the other, dodging supporting structures—a deadly game of survival.
Back at the devastated resort, Jack desperately tries to distract the panicking tourists, who are flooding toward the exits as flaming rocks begin raining down. Meanwhile, the nearby village faces a dire situation with locals fleeing for safety. Working with Meng and a researcher who chose to stay behind, they must devise a strategy to divert an advancing lava flow, which threatens to engulf the village, by unleashing water from a nearby reservoir. As they navigate countless obstacles in their jeep towards the control room, every second counts.
While Jack monitors multiple news broadcasts reporting on the ongoing calamity, he witnesses the despair of a little girl whose mother has perished. He hands her a keepsake from his own father instead of revealing the grim truth. Returning to save his wife, he is struck by falling debris.
As the team endeavors to reach the facility for water release, they're obstructed by flaming rocks. Fortunately, a drone positioned above the island becomes their salvation, successfully redirecting the flow of lava away from the village. However, it's a race against time as Meng yearns to locate her grandfather, only to find him unable to offer anything but a farewell.
Regret gnaws at Tao as he passes a memento of Meng's mother, revealing his anguish over past decisions. As a helicopter approaches, the group faces yet another challenge—a bridge crumbles beneath Tao before he can cross. Returning to base, like a phoenix, he grabs a motorcycle, only to ultimately vanish into the depths of disaster when ash clouds obscure him where his flare is launched.
On a nearby ship, Mrs. Harris spots the girl with the watch, inquiring about its origin, only to be told of her husband's demise. Yet hope flickers as news footage unveils Tao's miraculous rescue. An emotional reunion ensues between Meng and her father, interspersed with heart-tugging flashbacks of the bond they shared while he studied the volcano model. The conclusion rolls with Tao explaining his perilous journey to reunite with his daughter, leaving audiences with a sense of survival amid tragedy.
