A student joins an activist group that plans to stage a protest to protect the Amazon rainforest and its people. However, the clueless group eventually realizes that venturing into unfamiliar territory could cost them their lives. Deep in the Amazonian rainforest, two natives are out scavenging for food, when a loud monstrous noise sounds out before them.
All of a sudden, a bulldozer drives into view, demolishing the trees and flattening the land. Elsewhere, the student activist group "ACT" stages a rally and a hunger strike at the university grounds, fighting for janitors' healthcare rights. The members’ loud, chanting voices wake Justine in her dorm room, and she makes her way to the window to take a look at the commotion outside.
The noise also wakes Justine’s room mate, Kaycee, and her boyfriend, Scott, both grumbling in annoyance at the racket. Later, after the two friends buy some food, Kaycee expresses her irritation at the activist group’s righteousness. She believes their rallies are just for show, and that their activism isn’t really changing the world.
In class, the friends are appalled by their professors' lecture on the barbaric practices native tribes all over the world still perform on women. Horrified, Justine asks why the government hasn’t done anything to stop the practice and mentions that her father is a United Nations attorney. However, the professor says that even though corrective actions have been done before, outside forces can't fully intervene in a different country's customs and beliefs.
After the lecture, ACT member Jonah approaches Justine, and asks if she wants to join their group, which he says fights for the rights of oppressed people. Hesitant, Justine says she’ll think about it, so Jonah hands her a flyer with their next meeting’s location and time on it. At lunch, Justine and Kaycee meet with Charles, Justine's father.
She asks her father to try and help the women at risk of the barbaric practices, but gets discouraged when he says that meddling with another country’s affairs isn’t as easy as it sounds. To change the subject, Charles asks her about the necklace her mother gave her, the one made from her grandmother’s silver. Justine tells her father that she left it in her dorm room for safekeeping.
Later, Justine joins the ACT meeting where the leader, Alejandro, discusses their next mission, saving the lives of native people in the Amazon rainforest. The freshman asks the leader that if all they plan to do is stage a protest, do they really expect to enact change. However, she gets called out by Alejandro for being insolent.
Embarrassed, Justine walks out of the meeting despite Jonah's pleas for her to come back. That night, Justine reflects on her approach at the meeting earlier, and immediately takes her necklace, seeking comfort from its touch. The next day, the determined woman apologizes to Alejandro and asks him if she can join the group.
She wants to prove her willingness to go beyond their vision of attaining justice for oppressed people. Seeing her enthusiasm, the leader allows her to join another meeting. At the next ACT meeting, Justine listens to Alejandro's proposal for their next protest.
He says a petrochemical company is clearing the Amazon rainforest, and pushing the natives out of their homes. He explains that their group could bring the issue to the Peruvian government and worldwide media by exposing the atrocious activities by live streaming the event. After the session, Kara, Alejandro's girlfriend, approaches Justine, asking if her intentions are pure and because of a certain person, implying that she’s seen how the freshman looks at her boyfriend.
In response, Justine reiterates that she’s focused on the group's agenda. Afterward, Kaycee expresses her concerns regarding Justine’s safety, and says there are other things she can do to help without having to risk her life. However, Justine insists that she’ll be fine, and tells Kaycee not to worry.
Later, while Justine packs her stuff, she tries to convince her father through a phone call that she’s going on a school trip with other students. The woman cuts the call and rushes out of the building, with Kaycee following behind. Before leaving for the airport, Kaycee hugs her friend, warns her of the dangers she might face, and tells her to be safe.
At the airport, the group walks toward a small private plane, where they meet Carlos, their sponsor, who’ll accompany them on their way to Peru. Justine wonders why Carlos, who doesn’t look like the activist type, would pay for their mission, but Daniel tells her that Carlos is just a wealthy guy who believes in their cause. In Peru, the group rides in the local means of transport to reach their destination.
At the hotel, they regroup to discuss their plan and enjoy a meal. After eating, Kara distributes their shirts while Alejandro reminds them that they must keep filming because it’ll be their only means of defense against the petrochemical company and its militia. Realizing the enemy has hired gunmen, the members begin fearing for their safety, but Alejandro reminds them that nobody forced them to join the cause, and says they can back out now if they want to.
However, no one from the group dares to voice out. Soon, they arrive at the busy river port, where the students hurriedly run to the motor boats that’ll take them to the site. On the boat, Daniel warns Justine to stop using her phone and save her battery, since she won't get any signal until they reach the camp anyway.
He then shows her his GPS device that doesn’t need the internet to work, since it uses satellites. Stopping by the shore for a toilet break, Lars and Justine dash into the woods with a knife and gun. She returns earlier than the man, who panics after shooting at a tarantula that almost bit him.
Laughing at his misfortune, the group continues their three-hour boat ride. Later, they come across a jaguar resting by the riverside, and everyone is in awe of its beauty. Carlos explains that black jaguars are regarded as the guardians of nature, and believed to carry sinners to hell.
Alejandro takes the animal’s presence as a good omen for their team. Hours later, the group arrives, and everyone changes into neon worker suits and blue helmets, leaving their bags by the riverside. After dressing up, the group traverses the woods and eventually reach the site.
When their inside man gives them the cue, Alejandro distributes masks for everyone to wear. Soon, the group chain themselves to bulldozers and trees to officially start the protest. However, Justine has a defective padlock and calls out to Kara to help her.
The group starts filming the event, when an explosive detonates, destroying one of the bulldozers, cueing the members to chant, "This is the Yajes' home. " The petrochemical company's private militia arrives to remove the group from the site, but can't get them out of their chains. However, due to Justine's defective padlock, a man grabs her, pushes her to the ground, and points a gun at her head, threatening to shoot her if the others don’t cooperate.
However, Alejandro exclaims that people all over the world are watching the stream of the group's protest for the indigenous people's rights. He then tells the online audience that the militia is willing to slay the daughter of a UN attorney. Upon hearing this, the men hesitate to shoot, and eventually lower their guns.
After hearing Alejandro and Kara egging the militia on, seemingly with no concern for her life, Justine realizes that her defective padlock was all part of the couple’s plan, making sure she was the one threatened at gunpoint, so they can use her connections to the UN as leverage. The activists are then arrested and led back to the boats, where they discover that their bags are gone. When they reach the plane, Carlos bribes the police into releasing them.
On the plane, the group celebrates their successful protest, except for Justine, who disdainfully looks at Kara. They continue to celebrate as their video goes viral, making the Forest Stewardship Council take a step to file a complaint against the company, with the help of the Peruvian government. Suddenly, the engine explodes, and everyone rushes to get their seatbelts on as the plane descends.
Chaos erupts as the aircraft splits in two, and the scared passengers scream for their lives. Carlos and Brooke fall out off the plane from a great height, while the two pilots get impaled by the branches just as they crash. After the crash, Alejandro asks if everyone’s okay.
The confused group exits the plane, and Daniel says they must find his GPS to signal for help, since regular cell phones won't work in the jungle. The group begins looking around, when Kara hears a noise and investigates the nearby trees. However, since the group is dressed like petrochemical workers, the natives send an arrow through Kara’s neck, slaying the woman.
Alarmed, the group runs away, but they all get hit by poisoned darts that render them unconscious. Later, Justine wakes up on a boat with the headhunter and warrior rowing, and soon realizes that the other activists are in the same predicament. Reaching the village, the people with red-painted bodies welcome them by touching their bodies and thanking the spirits for the bounty.
Then the Village Elder enters and examines them one at a time, oddly smiling at Justine as if she approves of her. Then she orders the tribe to imprison the students in a pigpen. Meanwhile, the older women of the tribe offer Jonah a drink and lead him to an altar.
To the group's horror, the elder scoops out his eyeballs and tongue, before a man dismembers Jonah one limb at a time, before finally ending his suffering by decapitating him. Later, the villagers cook and eat Jonah while the group watches them fearfully. That night, Alejandro says they should expect bulldozers to arrive in the next few days, much to the group’s surprise.
He finally admits that Carlos works for a competing petrochemical company, and he hired Alejandro to stage the protest to get the original company off-site, allowing his employers to encroach on the area. The rest of the group are appalled that he would do such a thing, but he explains that the protest still garnered them media attention, which was what he wanted. He says that the rival company is expected to arrive within three days, and that they should be grateful that Jonah's flesh can feed the tribe for a week, further angering the group.
Samantha pacifies them by trying to escape through the top of the cage, but gets a dart from a warrior watching over them. The next day, Justine wakes up to see a native child playing with her necklace, and she entertains him by playing the miniature flute. Then the Headhunter and warriors enter the cage to pull all the women out.
The Village elder examines Amy, Samantha, and Justine to test their purity. However, only Justine passes the test, and they take her away to the Village elder's hut. Later, Daniel uses a ringing phone to distract the warrior watching them, and allow Samantha to escape to the boat by the river, where she hides.
The following day, Justine rejoins the group with ceremonial paint all over her body, and has no memory of what happened. However, Daniel realizes they want to perform a barbaric ritual on her private parts, which could lead to her bleeding out or an infection. Fearing the worst, he tells the others they must escape as soon as possible.
Later, Alejandro encourages the others to consume the food scraps the natives give to the pigs, because they’ll need the energy for the escape. Despite being vegan, Amy eats the food, but when she sees the familiar tattoos on the cooked skin, she realizes they just ate Samantha. Unable to live with the fact that she ate her lover, Amy breaks the bowl, grabs a shard, and cuts her own throat.
Aware that the natives will soon collect Amy’s lifeless body for their next meal, Lars and Daniel push a bag of illegal substances down her throat, hoping to intoxicate the tribe when they eat her. Later, the Headhunter takes Amy's corpse and prepares her meat for the village to feast on. Just like they planned, the entire tribe is dazed by the substance they consumed.
Lars, Daniel, and Justine try to escape, but Alejandro renders Lars unconscious with a poisoned dart, saying he needs someone to get eaten before him. Justine and Daniel have no other choice but to run away. Meanwhile, Lars wakes up to find that he’s outside the cage.
Unfortunately, because the illegal substance made the natives even hungrier, they feast on his flesh while he’s still alive. Elsewhere, the two escapees find pieces of their aircraft by the river and decide to follow the trail, when Justine accidentally falls into the raging river. Luckily, she’s able to grab hold of a rock and pull herself out.
Hours later, they come upon the crash site, where they discover the lifeless bodies of Kara, Carlos, and Brooke impaled by the tribe. Daniel finds his GPS but it’s run out of power. They hear a working device on Kara's body, but as they try to retrieve it, the Yajes recapture and bring them back to the village.
The following day, Justine wakes up being lathered with an oily substance. Meanwhile, Daniel cries in pain as they tie him up on a stake and break his bones with a blunt weapon. The natives start painting the woman's body, while the men slather a green-colored substance all over Daniel that attracts ants, and the insect bites cause him immeasurable pain.
In the hut, the Village elder is about to perform the barbaric ritual on Justine, when suddenly, a warrior appears with a worker's head, alerting the tribe of a new clearing crew's arrival. The warriors all gather at the order of the Headhunter. Seeing that the adult Yajes have left, Alejandro tries to make a run for it, but the two young guards hinder him.
In the hut, the Yajes child Justine befriended helps her escape her ropes, and she overpowers the woman guarding her. Outside, Justine approaches Daniel at the stake, who tells her to take the phone, and begs her to end his life. Seeing the hesitant woman, the child ends Daniel’s misery for her.
Just before escaping, Justine hears Alejandro’s pleas for help, but she ignores his cries and abandons him. In the forest, the child guides her to the path of freedom, and as a token of gratitude, she gives her flute necklace to the child. Reaching the river, Justine encounters a black jaguar and bravely crosses to the other side.
Two natives are about to stop her, but they take the animal’s presence as a sign to let the woman go. At the clearing, the woman witnesses the militia slaying the Yajes warriors with guns and explosives. So, Justine shouts that she’s an American whose father works for the UN, and pretends that she’s filming the event on her phone.
Then the woman pretends that she’s breaking the phone by throwing it to the ground after sending the video to the internet. They take her to the helicopter and ask if there are any other survivors. Justine lies and says she’s the only one left, leaving Alejandro in the hands of the Yajes tribe, who screams for help when he sees the helicopter.
Days later, Justine lies to her father and government officials about being the only survivor of the plane crash. She says that the Yajes were friendly people, who helped her before the clearing crew arrived, and that the militia slaughtered the natives. Days pass, and Justine still suffers from nightmares of her harrowing experience.
One day, she wakes up to the sounds of another ACT rally, and when she looks out the window, she sees the members wearing shirts with Alejandro's face on them. Days later, Justine receives a phone call from an unfamiliar woman. She introduces herself as Lucia, Alejandro’s sister.
She says she was able to find satellite images of a person who looks like her brother, and tells Justine that they need to talk.
