During a raging forest fire in northern Wyoming, Jesse Graves, a skilled smokejumper, teams up with his veteran mentor, Wynt Perkins, to rescue trapped civilians. As they push through smoke and collapse-prone structures, a frightened woman pleads for them to save her daughter from a burning cabin. They locate the girl, but the mission takes a brutal turn when a travel trailer is hurled by an explosion, injuring Wynt. Jesse manages to pull both his partner and the girl to safety from a sudden flashover. The injuries force Wynt into retirement, yet he is hesitant to accept a complete exit from duty because of a shaky pension plan and a lingering sense of duty.
Months slip by, and a desperate escape plan unfolds. A group of prisoners, aided by an arsonist outside, masterminds an escape by reigniting a forest fire to lure fire crews into a trap and grant them freedom. Among the escapees is Randall Shaye, a man who once vanished with a fortune of US$37 million and claims a new identity as the band regroups. They pose as Canadian firefighters and snatch Jennifer, a bird watcher with a concealed past as a Marine, as they weave through the trees. Unseen by the convicts, a separate blaze begins to burn, sparked by a lightning strike a week earlier, threatening to engulf everything.
Determined to stop the impostor firefighters, Jesse must outsmart Shaye and the other fugitives while racing against the expanding fires to save Jennifer. Shaye methodically eliminates his allies to keep the money for himself, wasting no time with traitors like Wilkins and Karge as the flames close in. When the truth comes out that the money never survived the blaze, Shaye’s grip tightens, and he pushes Loomis off a cliff to stage an accident and remove a rival. He also shoots Packer after a spring trap set by Jesse ensnares him, narrowing his options even as Wynt does whatever he can to help his old protégé and to secure Jennifer’s safety.
As the two former allies—Jesse and Jennifer—attempt to escape, they attempt to signal friends using smoke to find them before the two fires merge and drain the available oxygen. Wynt arrives just in time to rescue a busload of prisoners and firefighters when they are forced at gunpoint into the vehicle, hotwiring the bus to get everyone to safety. He catches up with Jesse, and together they devise a plan to survive the inferno.
Despite the revelation that Wynt may have known about the fire from the start to aid a land developer seeking a firefighter training school, he insists the truth stays buried to protect his friend. A tense confrontation erupts when Shaye’s schemes are laid bare, and Jesse’s resolve hardens. In a climactic struggle, Shaye is fatally defeated when Jesse drives a fire axe into his chest and he tumbles from a boat into the flames. The firestorm roars on, but a heavy rainstorm finally begins to douse the blaze, allowing Jesse and Jennifer to cling to the boat as a lifeline. They swim to shore as the flames fade, waiting for rescue, while a hopeful note arrives as Jennifer realizes the eggs she carried have hatched, a quiet, uplifting sign amid the chaos.
