A team of dedicated researchers embarks on an adventurous quest deep into the jungles of Padrang, located in Borneo, Indonesia, with hopes of discovering a rare blood orchid—a flower they speculate might serve as a kind of "fountain of youth." Despite having doubts about the safest route, the team's guide, Bill Johnson, is bribed by Jack Byron ([Morris Chestnut]) to take a treacherous path. This risky choice leads to a dramatic plunge into a river after a waterfall, where they encounter an intimidating presence: a massive anaconda that swiftly devours Dr. Ben Douglas ([Nicholas Gonzalez]) whole.
Bill attempts to reassure the group about their perilous situation, asserting it will take weeks for the snake to be hungry again, yet the tension escalates, and many demand to call off the expedition. They decide to seek assistance from Bill's friend John Livingston, who lives along the river, hoping to borrow his boat. During their journey, Bill reveals to Sam that he was coerced into taking the unstable path by Jack. Their trek quickly turns gruesome when they discover a painful leech infestation on Cole’s back, which Bill cauterizes with a lighter, while Tran finds a dangerous spider lurking in Gordon Mitchell's ([Eugene Byrd]) shoe. Jack, intrigued by the spider, chooses to keep it for further research, and they continue their perilous venture to locate the boat.
Tragedy strikes when they reach Livingston's location, only to discover that he has been killed by another anaconda, causing their boat to crash into the unforgiving riverbank. As they survey the wreckage, they are visibly defeated for having lost their chance of escape, only recovering a few essentials for their ongoing expedition. The horror deepens when they come across Livingston’s mutilated corpse. Bill realizes that it's mating season for the anacondas, meaning the males will be aggressively searching for females, increasing their danger.
Venturing further, they stumble upon a small native village where a gruesome display presents an anaconda with human remains protruding from its belly. This frightful discovery leads the team to speculate that the snakes have grown to enormous sizes due to the blood orchids, which play a vital role in the local ecosystem. Jack insists they must be close to the orchids, igniting conflict among the group—some want to press forward, while others, unconvinced by Jack’s theories, begin constructing a raft for their escape.
As tensions flare, Gordon realizes that Jack had kept a radio and a firearm from Livingston that could’ve summoned help long ago. When confrontation arises, Jack retaliates by incapacitating Gordon with the spider's venom. Meanwhile, an anaconda ambushes the team as chaos ensues, and after a furious fire set to divert attention, Jack seizes the opportunity to commandeer the raft. With materials for another raft exhausted, the remaining team members must battle through the jungle to beat Jack to the orchids and reclaim their chance at survival.
Their journey turns chaotic as they plunge into a cave while trying to evade the menacing snake. Things take a darker turn when Cole becomes disoriented and uncovers a terrifying skeleton, adding to their anxiety. Tran’s misfortunes lead him to deadly depths, as an anaconda drags him below the water’s surface, leaving Cole to escape just in time with the rest of the group.
In a final struggle against the anaconda, Sam valiantly uses a machete to sever the snake's head, yet Cole finds himself ensnared by another giant serpent. With desperate bravery, Bill hurls a knife into the anaconda, rescuing Cole from its grip.
Just when it seems they could finally leave, Jack manages to locate the coveted blood orchids, precariously dangling above a mating pit of male anacondas. In a bid for control, he forces Sam to navigate a tight log bridge to collect orchids for him, igniting a fierce struggle that culminates in her almost falling into the snake pit. As the scene spirals into chaos, the very spider that Jack had used flees its containment and bites him, resulting in his downfall into the pit where he meets a grim fate at the hands of the anacondas.
As the chaos settles, the group must confront a final threat: a ferocious female anaconda. In a stroke of luck, they manage to distract it, but when Bill's gun fails to fire, Cole takes the initiative to aim a flare, triggering an explosion that eradicates both the snakes and the orchids. In the aftermath, Bill, Sam, Cole, and Gail along with Bill’s pet monkey, Kong, finally set off down the river on their raft, leaving the horrifying jungle behind. As they drift away, Bill proposes another shortcut—yet the others adamantly refuse to follow his questionable leadership again.
