The movie begins with a truck driving through the desert, carrying 14 people in the back. It turns out that these are Mexican immigrants illegally crossing the US border in search of a better life. Among them is a man named Moises, who is holding a teddy bear; the toy is making sounds and he doesn't know how to turn it off.
A man instructs him to press its tummy, and it immediately stops making noise. Unfortunately, while driving across a barren expanse of desert, the truck suddenly breaks down. The driver, Lobo, gets out to check, and asks the immigrant group if any of them can repair the truck.
Moises raises his hand and claims that he is a mechanic. He approaches the front of the truck to inspect the engine, and discovers that the engine has been destroyed and cannot be repaired. With no other option, Lobo suggests that they continue their journey on foot through the badlands.
One of his friends, Mechas, warns that it’s a dangerous route where an entire gang was recently slaughtered. However, Lobo reassures him that they were killed as a result of drug dealings with cartel members. Mechas is still hesitant, but Lobo eventually convinces him by promising him more money.
He then points the immigrants in the direction of the United States and asks all of them to get off the truck. The group now has no choice, but to walk across the desert to get to their destination. Elsewhere in the desert, we see an American man named Sam driving a truck while drinking alcohol.
He is accompanied by his beloved, fierce dog, Tracker, and the two have set out to find a rabbit for lunch. Shortly after, the immigrants arrive at the frontier, which is covered with barbed wire. Lobo reveals that now, they will be stepping into the United States.
He emphasizes the need for caution and says that if they hear even the slightest sound, they must immediately hide. The group agrees, and they cross the barrier one by one, making it to the other side. In another scene, we see Sam grab his rifle, and fire at a figure in the distance.
The gunshot echoes throughout the area, causing tension among the immigrants, who seek refuge in a field covered with cactus and rolling shrubs. However, it turns out that Sam had only killed a rabbit for his meal. After a while, the group believes the threat has passed and sits down to rest, drinking some water.
During this time, a man harasses an immigrant named Adela and attempts to flirt with her. She claims that he is not her husband, and that her parents only asked him to look after her. Seeing this, Moises intervenes and distracts the man to prevent him from crossing his limits.
The group then gets up and resumes their journey. Meanwhile, Sam is driving through the same area, right when he encounters a patrol officer. The latter asks him what he is doing so close to the border and if he has a permit.
Sam laughs it off and wonders if he needs a permit just to hunt rabbits, so the officer says he doesn't. Here, Sam claims that he had filed a report about illegal immigrants infiltrating this area, and questions whether the cops conducted any investigation. The officer responds that he is unaware of the situation, which appears to frustrate Sam.
In the next scene, the immigrants have been split into two groups. One group, led by Lobo, is moving quickly, and has gotten quite far ahead. Then there’s the slower group, which includes Moises, Adela, Mechas, and two others.
Mechas yells at Lobo to slow down and wait for them, but the latter just laughs and ignores him. He blames them for moving too slowly and encourages his group to walk faster. Just then, the slower group notices Sam’s truck from an elevated viewpoint on a hill and quickly hides.
Moments later, Sam exits his truck, and discovers a handkerchief lying on the ground. He gives it to Tracker to sniff, and orders him to find out if there's someone nearby. Soon after, they spot the immigrant group led by Lobo walking in the distance.
Sam takes his rifle, aiming at one of them… Everyone is taken aback when bullets appear out of nowhere, but Sam is overjoyed to see a group of people fleeing for their lives. He proceeds to shoot at them one by one. The group frantically runs through the vast desert to save themselves, but Sam ends up shooting them all.
Meanwhile, Moises’ group watches the man killing everyone from a distance, and is horrified by the gruesome scene. After killing them all, Sam congratulates himself on his victory. The psychopath harbors a deep hatred for illegal immigrants, and takes great pleasure in killing them with his own hands.
During this, Tracker continues to bark aggressively toward the direction Moises’s group is heading. Sam then notices a few people heading over a hill, and decides that he should kill them as well. Shortly after, Sam arrives at the end of the road, where he exits his vehicle and asks Tracker to locate the group.
He follows behind his dog with a rifle in hand. The group soon notices the vicious dog chasing after them, prompting them to run away. Moments later, the man who was earlier harassing Adela drops his backpack and rushes to pick it up.
As a result, he falls behind his group, and Tracker eventually catches up to him. Adela notices this and rushes to help the man, but Moises stops her because it’s too late. Tracker viciously rips the man's throat and ends up killing him.
After this, the remaining four people continue to ascend uphill while Tracker chases after them. They then climb up to a tree, and make it to the other side of the hill. Tracker also tries but is unsuccessful, so he begins looking for other ways to climb.
Soon, the damn dog finds another path, and he continues to chase after them. Sam also climbs to the top of the hill, and gets a view of Moises & his companions. Sometime later, the group arrives at a ditch, and to save themselves, they have to jump from one huge rock to another.
Realizing that Tracker is closely behind, they have no option but to take the risk. Moises, Adela, and Mechas successfully make the jump, and arrive at the other side. But the fourth guy is very scared and lacks the courage to do it.
He sees Tracker in the distance and bravely attempts to jump to the other rock. Unfortunately, he barely clings onto the rock and, at this moment, Sam shoots the man with his rifle, causing him to fall to the ground. The bullet doesn’t hit Moises, and he runs away with the rest of the survivors.
After this, Sam begins studying the map of this area to predict their escape route. He then commands his loyal dog to chase after the remaining three immigrants, and Tracker starts running off, while Sam hops into his truck and begins driving. Later on, the group notices Sam in his truck, but he doesn't see them as they’re hiding in the canyon.
Sam then exits his car and begins looking around the area. Unfortunately, Tracker notices the immigrants from a distance, and begins barking aggressively. The three proceed to climb up the rock again, and attempt to escape from there.
But because of Tracker’s continuous barking, Sam becomes alert, and he also begins to climb the canyon. He soon notices Mechas, who has fallen slightly behind Moises and Adela, and the nervous guy ends up falling to the ground below. Seeing this, Sam climbs down the rock and shoots Mechas in the head to finish him.
Now, the only survivors left are Moises and Adela, who are still hiding behind the canyon. All of a sudden, the teddy bear in Moises' backpack starts to play music, so he quickly turns it off. Tracker and Sam hear this and they have a strong suspicion that the two are still nearby.
But Sam is worn out from the long day, and night is falling soon, so he decides to leave for the time being and continue his hunt tomorrow. In the evening, Moises expresses sorrow for the death of her male friend, but Adela responds that she hasn't known him for that long. She explains that she didn't want to come here, but her parents thought their town was not safe for her.
Moises then reveals that he used to illegally live in America with his wife and son. One day, he was stopped by a cop because of a broken headlight, which led to his arrest. He initially tried to leave the country through the proper procedures, but was belittled by local police and thrown into a detention center.
The teddy bear was given to him by his son during his deportation. Moises promised to return someday; he is willing to do anything to reunite with his son. The next morning, Adela goes to the top of the hill, and notices Sam with his truck from a distance.
She then turns back to find Moises, but on the way, she is startled by the presence of rattlesnakes in large quantities. Despite this, the girl cautiously moves in a different direction, narrowly avoiding a snake bite. When she finds Moises, she tells him about her plan to steal the white man’s truck and drive away from there.
Moises is nervous and insists they need to get rid of the dog first, so Adela assures him that she has a plan and just needs his teddy bear. In the next scene, we see Sam gathering his stuff while Tracker is sleeping on the ground. Suddenly, the dog wakes up, and begins to run off somewhere.
Sam assumes that the immigrants are nearby, so he follows it with his rifle. They reach the top of the hill, only to find the teddy bear playing music and surrounded by snakes. Sam then notices the immigrants heading to his car.
He tries to fire at them, but is interrupted by a snake. Here, Sam then starts firing at the duo from a distance, but he misses each shot. Moises grabs the antenna on the vehicle and uses it to open the front door.
They manage to get inside and close the windows while Tracker begins to find a way to just bite them. Fortunately, Moises starts the truck just in time, and drives away from there. The immigrants are overjoyed that they have finally gotten away, and begin to celebrate their victory.
However, their happiness is short-lived… Sam suddenly shoots at the truck, hitting Adela in the shoulder, and sends Moises into a state of panic, resulting in an accident. Luckily, Moises manages to get out of the truck, unharmed. He then helps the injured Adela out, and grabs a first-aid kit from the truck; the two quickly flee from there.
After walking for a while, they arrive in front of a giant cactus and decide to rest there. Moises opens the first aid kit, where he finds a bandage and a flare gun. He tends to Adela’s wound, and tells her that he has to leave her alone.
Moises asserts that if he stays, they’ll both die, and he is determined to see his son again. Sometime later, Sam and Tracker notice the blood trail, and soon arrive at the huge cactus where Adela is resting. Adela notices their presence and tries her best to hide herself.
At this tense moment, Moises fires a flare gun in the distance and provokes Sam to come after him. The latter instructs Tracker to go after Moises, stating that the girl is injured and will die soon anyway. After this, Moises begins to run toward the cactus fields, while Tracker chases after him.
Moises takes the decisive step of cautiously making his way through the thicket of cactus. While this is happening, the dog keeps running at a high speed, and eventually manages to catch up, but Moise shoots the last flare bullet straight into his mouth. This causes the dog to squirm in pain, while being stuck between the cactuses.
Moises then takes advantage of the opportunity to escape. On the other hand, Sam hears his dog whimpering, and is devastated when he discovers Tracker in a burned state. To end his suffering, he ends up shooting Tracker.
After the death of his beloved dog, Sam composes himself and swears revenge on the guy who did this. Meanwhile, Moises spots a border patrol vehicle in the distance. He yells for help, but fails to get its attention.
Sam notices him and begins to fire multiple times, but Moises manages to evade the shots. The poor immigrant hides in the bushes, begging for help while crying. Shortly after, Moises starts climbing up another rock hill to get away from Sam.
The latter continues to chase after him, while Moises hides behind the canyon. The two of them circle around the canyon, and after a long game of pursuit, Sam finally stops at the edge of one of the cliffs. Hiding just right behind Sam, Moises realizes it's his only chance to defeat him, so he tackles Samm off of the mountain.
Both men hit the side of the mountain and roll down it. Due to the fall, Sam is badly injured, and he notices a bone poking out from his skin, while Moises appears to be fine. The two notice that Sam’s rifle is just a short distance away, and Moises is able to get his hands on the gun.
He points it at Sam, and confronts him about how he killed his companions like they were animals. Sam, who is on the verge of death, apologizes for his actions and begs for his life. Despite what Sam did, Moises decides not to kill him and begins to walk away, thinking that the desert will kill him slowly.
In the final scene, Moises goes to find Adela, who is still behind the cactus and in a critical condition. She appears to be in a dazed state and he asks her not to lose hope. Moises carries her on his back and assures her that they are almost there.
After walking for a whole day, Moises sees flickering lights in the distance, which implies they have finally made it to the city. And this is where the movie ends.
