NOTE: This spoiler was sent in by Marcus.

The film begins with a woman sitting in the dark, cradling her legs and cell phone. She screams for someone to help her, but no one does. She’s quickly pulled away by something in the dark and screams. Elsewhere, Jeff (Jonathan Tucker) and Stacy (Laura Ramsey) play cards while sitting poolside at their hotel. Jeff’s girlfriend Amy (Jena Malone) sunbathes as Stacy’s boyfriend Eric (Shawn Ashmore) brings everyone more drinks. Jeff doesn’t want to drink, and everyone laughs while talking about the previous night, where a drunken Jeff decided to act as lifeguard for the group while he was naked. Amy realizes that one of her earrings is missing and she looks around for it. Mathias (Joe Anderson) sees her from across the pool, grabs a snorkel, and jumps in the pool. He pops up on the other side and gives Amy her earring, since he found it in the pool. She thanks him, and then the group invites him to stay and hang out. Mathias is there in Mexico with his brother Heinrich, but he hasn’t seen him in a while. He’s not worried though, since Heinrich met a girl who’s an archaeologist and he’s probably still with her. Tomorrow, Mathias will go to the Mayan temple where they are and invites the group to go along with him. Jeff is enthusiastic about going, since he’s tired of partying and drinking all the time. He’d like to see some culture before they leave in a couple of days, and soon the rest of the group agrees to go. Dimitri (Dimitri Baveas) jumps in the pool with his Greek friends, and Mathias says that they’re also going to come with them tomorrow.

That night, Amy takes a picture of the group while they sit on the beach. Amy gets really drunk and wants Jeff to dance with her. He doesn’t feel like it, and so she falls onto the sand. He goes over to her and tells her that she should get some sleep, but she says that she’s having a really good time. Jeff (who’s a medical school student) decides to call it a night and goes back to his room. Amy gets Mathias to dance with her as Eric bets that she will end up kissing him. Stacy doesn’t think she will, and so they agree that the winner of the bet gets oral sex. Amy winds up kissing Mathias, but he quickly signals Stacy over to get her off of him. Eric laughs since he won the bet. The next morning, Jeff jogs on the beach and passes by Dimitri’s passed out Greek friends. He meets up with Dimitri and Mathias at breakfast. Mathias makes a map for the Greeks to join them whenever they wake up, and Dimitri puts the map underneath one of their heads. Jeff and Mathias plan to meet in the lobby in half an hour with the others. Stacy gets out of the shower and quickly puts on her underwear, telling Eric that she doesn’t want to be late. He tells her that he wants to collect on their bet, and she is eventually convinced to give him a blowjob. Meanwhile, Amy vomits in the toilet from drinking too much last night, and Jeff steps out of the shower. He quickly gets dressed and wants Amy to hurry up too, but she wants to stay behind. He says that he doesn’t want to go unless she goes too, and so she agrees to go. Stacy and Eric knock on their door, with Eric being especially happy from his bj.

Jeff, Amy, Eric, Stacy, Mathias, and Dimitri take a bus to a village. They have to get a taxi to take them into the jungle and to the temple. They eventually find a taxi truck, and the dog in the back startles them. Mathias shows the driver where they want to go, but the driver doesn’t want to take them there. He only agrees to drive them once Dimitri gives him a wad of cash. Everyone gets in the back of the truck, and Stacy’s hat flies off on the journey. The driver takes them off the road, through the jungle, and to a clearing. He drops them off and drives off. Amy wonders how they’ll get back, but the others say that they’ll just call him back (Mathias has a cell phone that has a signal). Mathias recognizes Heinrich’s jeep, but doesn’t see him. The group hikes into the jungle and follow the directions Heinrich left Mathias. They have to cross a river and then follow a path on the other side. If they come across a Mayan village, they’ve gone too far. They get to the river and they see two Mayan children watching them from afar. They try to talk to the kids, but they won’t respond and they won’t come any closer to them. Mathias finds the path that they need to take, and one of the kids runs off into the jungle. Amy gets a bad feeling because the path was hidden by bushes/branches. The others say that the archaeologist probably found something valuable, which is why the path would be blocked off. Everyone goes through the path and then they eventually make their way to a big Mayan temple, which is mostly covered with plants and vines.

Mathias sees a tent at the top and calls out for Heinrich. Amy starts to take pictures when a Mayan rides a horse to the temple and gets off. He yells at them, but no one understands what he’s saying. Soon enough more Mayans appear, armed with bow and arrows and pistols. Mathias shows the lead Mayan a picture of his brother on his cell phone, asking if they’ve seen him. As he does, Amy nervously takes pictures and steps onto the vines of the temple. The Mayans freak out because of this, and Dimitri thinks that they’re upset because of her camera. He too steps on the vines to get the camera, and he offers it to the Mayans. Dimitri is shot in the chest with an arrow, and then a chunk of his head is blown off with a pistol. Everyone freaks out, and the Mayans force them back. The group runs up the temple and Mathias frantically searches for his brother. They look through the tents set up at the top, but no one’s there. Jeff says that they should call for help, but the Mayans still have Mathias’ cell phone and Eric doesn’t have a signal, which pisses Amy off (since he was joking earlier that he had a signal). Jeff says that all they need to do is wait and someone will come for them, like the Greeks. Also, Jeff has them save their water and food, since they don’t have enough to even last a day. The group then hears a cell phone ringing from inside the temple. Mathias volunteers to go inside and get it. Jeff and Eric tie a rope around Mathias, and then they lower him into the temple by using a crank. While being lowered, the rope begins to break. Amy warns Jeff of this, and so they try to lift Mathias back up but it’s too late. The rope breaks, and Mathias falls deep into the temple, causing a loud thud when he hits the bottom.

Eric can hear Mathias in pain at the bottom of the temple. Jeff says that one of the girls will have to be lowered inside so that they can help Mathias. Amy asks why it has to be one of them, and Jeff says that he and Eric are strong enough to work the crank for the rope. Stacy agrees to do it, and ties rope around her body. The plan is that once she gets to the bottom, she’ll put Mathias in the rope harness and they’ll lift him back up. Stacy is lowered into the temple and gets close to the bottom when the guys stop. There’s no more rope, and so Stacy will have to jump down to the ground. She frees herself and jumps, cutting her knee in the process. She gets to Mathias, and he says that he can’t feel his legs. Stacy shouts out to the others that he broke his back. Jeff and Eric decide to make a stretcher for Mathias and use materials all around them, including parts of the tents. Amy freaks out and says that the Mayans have to help them. She runs to the base of the temple as the Mayans point their weapons at her. Jeff runs after her, and Amy urges him to communicate with the Mayans. Jeff says that they don’t understand what they’re saying and tries to comfort her, but she snaps and throws a clump of vines at the Mayans, screaming and asking why they won’t help them. The vines hit a Mayan boy, and the others quickly turn on him. They yell at the boy while the boy’s mother watches. The lead Mayan shoots the boy dead, which causes Amy and Jeff to retreat back up the temple. While waiting for the stretcher, Stacy hears the phone ringing again. She tries to look for it but can’t find it. Jeff and Eric rig the stretcher to the rope, and then Amy is lowered into the temple with it. Since the stretcher can’t make it to the ground, the girls will have to lift Mathias and put him on the stretcher. When they pick him up, he screams in pain as his body contorts. The girls strap him in and the guys lift Mathias back up.

After everyone is brought back to the top, Jeff inspects Mathias. His back is broken, and they have to keep his legs clean or else he could die of bacteria infection. He also doesn’t want to risk moving him again, and so he has everyone search through the tents for aspirin. Amy finds the keys to Heinrich’s jeep, but not much else. Jeff finds Dimitri’s plane ticket, which says that his flight is tomorrow. Once they don’t return to their hotel and make the flight, his friends will come looking for them and bring help. All they have to do is make it through the night. Scared, the girls sleep together as Jeff goes down near the base of the temple and observes the Mayans, who have set up camp and are watching his every move. The next day, Jeff and Eric lower Stacy and Amy into the temple again. They give the girls torches and matches so that they can find the cell phone. Once at the bottom, they light the torches and go deeper into the temple. Stacy doesn’t want to go, but Amy tells her that they have to get the phone. Deeper and deeper in the temple, they find that plants and vines cover mostly everything. The girls hear the phone ringing again, and try to find it. Eventually, they get to a room and find the woman from the beginning (Heinrich’s archaeologist girlfriend). They see that she is dead, and her body is mutilated. They grab the cell phone from her hands, but then see that it’s broken. The girls are confused, and then they hear a phone ringing again. Amy follows the ringing and then sees that the flowers around them are vibrating and mimicking the ringing. The vines suddenly spring to life and attack the girls. They snatch away the torches and try to consume the girls. Stacy and Amy run off and make it back to the rope, screaming for the guys to lift them back up. The vines try to kill the girls, but they make it back on top of the temple.

The girls tell the guys what happened, and how the plants were mimicking the phone ringing. They realize that the reason why the Mayans are keeping them there is because they all touched the vines and they’re being quarantined. Eric wants to make a run for the jeep, but Jeff won’t let him. It’s too dangerous, and if they try to leave the Mayans will kill them. He maintains that they just have to wait for help to come. Eric says that the Greeks are not coming, but Jeff persists that they will. He says that four Americans can’t just disappear while on vacation, and that someone will find them. They just have to be alive when they do. Later, Jeff urinates on the edge of the temple when he sees something moving in the plants. He looks closer and finds Heinrich’s corpse hidden within the vines. Amy comes up to him and embraces him from behind. Stacy wakes up next to Eric and feels something strange. She lifts her blanket and finds that there are vines slithering into her leg wound. She freaks out and wakes up Eric, who clears the vines away and pulls out the ones from her leg. While Jeff goes over to see what’s going on, Mathias urges Amy to help him. There’s something on his legs, and when she removes his blanket she sees that the vines are eating them away. Jeff runs over and swaps the vines away. Stacy says that she can still feel the vines inside of her, but Eric tells her that he got them all out.

Later on, the group divides a sandwich to eat and they each take one drink of water. Jeff brings Mathias some water and then inspects his legs again. He walks back to the others and says that they need to cut off Mathias’ legs. There’s no flesh covering his legs, and he will definitely get bacteria infection. They have to break the legs first before they can cut them off. All they have to cut with is a knife. Amy and Eric can’t believe that Jeff’s seriously considering doing this. Eric says that they should vote on it. Jeff and Stacy vote for surgery, along with Mathias. Jeff tells the girls to wait in the tent. Since Mathias is paralyzed, he shouldn’t feel anything. Jeff gives him a belt to bite down on in case he wants to. Eric holds his feet as Jeff heats up a rock on a hot pan. He grabs the rock and then breaks Mathias’ leg with it. Mathias screams in pain, and then Jeff cuts the leg off by using the knife. He has Eric hold Mathias down as he does this, and then Jeff puts the hot pan on the stump to stop the bleeding. The girls and the Mayans hear as Jeff breaks the other leg and severs it. The girls come out of the tent just in time to see Jeff putting the hot pan on the other stump. They get upset since he wasn’t supposed to feel anything, but what’s done is done. Then the group is startled to see the vines snatching Mathias’ severed legs and eating them.

That night, Stacy keeps telling Amy that she can feel the vines inside her. Amy tries to calm her down and gets her to go to sleep. Amy then goes outside and sits by Eric. She tells him about Stacy, but Eric says that he got out all the vines from her wound. Amy asks him if he thinks they’ll be rescued, but Eric honestly doesn’t think so. He thinks that the only chance they have is if they make a run for the jeep. Amy cries and Eric holds her to comfort her. Stacy wakes up, having heard Amy outside. She gets out of the tent and accuses Eric of having sex with Amy. They tell her that she’s acting irrational and crazy, but she says that she heard them having sex just now. Jeff, who was again watching the Mayans, comes back to the top and asks them what’s going on. Stacy says that Amy is cheating on him with Eric. While everyone argues, the vines slither to Mathias. Stacy tells Jeff that Amy kissed Mathias, and then they hear him struggling. Jeff runs over to Mathias and sees that the vines have slithered down his throat and up his nose. He pulls them out, but it’s too late. Mathias is dead. Eric sarcastically says “well thank god we cut off his legs”. Stacy says that there are vines in her, and when no one believes her she screams “you’re not listening”. The plants and flowers all around them then begin to mimic Stacy’s voice, and repeat “you’re not listening” over and over again, surrounding them with the noise.

The next day, Amy sits by Jeff at an edge of the temple. Jeff says that the temple must be old, since animals have learned not to go near it. He also notes that the Mayans cover the surround areas with salt to make sure the vines don’t venture past the temple. Amy says that she didn’t cheat on him, but he doesn’t care either way. He just wants them to be alright. Eric calls them over to a tent, and he has Stacy show them her back. She lifts up her shirt and they all see that there are vines underneath her skin, in her back and in her leg. Jeff gives Stacy tequila and then puts some on her leg. He says that it’s maybe for the best if she doesn’t look, but she wants to see the vines get pulled out. Jeff thus digs the knife into her leg, and then digs around in her leg with his fingers until he gets the vine out. Stacy screams in pain, and Jeff asks her if she wants to stop. She says no, and then turns over onto her stomach. Jeff puts alcohol on her back and then carves an X into her back side. Again, he puts his fingers in the wound and gets the vines out while Stacy howls in pain. Jeff cleans up the wounds and they all sit down together. Eric tells Stacy that she’s going to be alright, but she insists that there are still vines in her body and head. Amy tells her to drink some tequila, and as she takes a swig the others see a vine slithering in her forehead. They all look away, and Stacy realizes that they saw the vine. She wants to do some more cutting, saying “just one more cut”. She tries to take the knife from Jeff, but he refuses.

Later on, while everyone sleeps in the same tent, Stacy wakes up and limps out. She looks around and finds the knife. The plants and flowers near her mimic her voice again, saying “just one more cut”, surrounding her with her own voice. The others soon wake up and see Stacy from afar. She has mutilated her body and has cut very deeply into her thighs, side, and forehead. Jeff tries to get her to stop and tries to get the knife away, but Stacy slashes his hand and then continues to cut into herself. Eric tries to calm her down, but she snaps, turning around and stabbing him in the chest. Shocked, Eric falls down and Jeff tries to help him. Stacy says that she didn’t mean to stab him and holds Eric’s hand as he dies. Suddenly, the vines start to drag off Eric’s body to be eaten. Jeff tries to get the vines away from the body, but the vines are too strong. Stacy begs for Jeff to kill her. Before Eric is completely consumed, Jeff grabs the knife from his chest. The Mayans hear Stacy scream and then hear Jeff stab/kill her. Jeff then smears blood all over Amy’s body, telling her that she has to make a run for the jeep. He’s going to bring her down to the base of the temple, and he’ll distract the Mayans so that she can escape. He promises that he’ll still be there when she returns with help.

Jeff carries Amy to down the temple and lays her on the salted ground. He kisses her goodbye and then slowly starts to lead the Mayans away. He says that they don’t even know their names. He says that his name is Jeff and says where he’s from. He then says that they should know Amy’s name, since she’s not going to die there. The Mayans threaten Jeff with their weapons. He yells out Amy, which makes her get up and run off into the jungle. Jeff is shot twice in the chest and once in the leg with arrows by the Mayans. The majority of them chase after Amy while the lead Mayan remains behind with Jeff. The vines wrap around Jeff’s body and start to consume him alive. The lead Mayan shoots Jeff in the head to put him out of his misery. Amy hears the gunshot, and then the Mayans try to shoot her as she runs through the jungle. She makes it to the jeep, starts it up, and speeds off. She drives back to the road and starts to drive back into town, distraught by everything that’s happened.

The film ends with the Greeks showing up to the temple, wondering where Dimitri is (which implies that they will soon become the next victims).