The scene changes to Andrew Kaulder (Scoot McNairy), a young American photojournalist, who is hired by his wealthy employer to get the latter's daughter Samantha Wynden (Whitney Able) back to the United States from San José, Central America. Andrew has no interest in being an escort but is pressured into doing so by his employers, while Samantha seems at odds with her impending marriage to her fiancé. He locates Samantha in a Mexican hospital, where she is being treated for an injured wrist.After leaving the hospital, the pair board a train to reach the Mexican coast, where they plan to take a ferry to the United States. However, the pair are temporarily slowed down by the destruction of the railroad. They learn that if they do not leave the country within a few days, sea and air travel will be blocked, and they will have to wait six months before safe travel is possible. With that deadline looming, Andrew makes the decision to walk the rest of the way to the Coast, which Samantha regretfully complies with. After spending the night with a generous local family, the pair make their way to the eastern gulf coast of Mexico.
Arriving at the port, Andrew buys Samantha a single ferry ticket, at a notably inflated price, for the next morning at 7 o'clock. That night, they explore the town's night-life: drinking, eating and having a good time together, but upon returning to the hotel, it soon becomes obvious Samantha wants to go to bed alone. Andrew resumes drinking heavily throughout the night after she turns him away from her room. The next morning, Samantha is unable to get on the ferry, since Andrew was robbed of their passports by the local girl with whom he spent the night. Given no other option to return home, Samantha barters her engagement ring in exchange for an escort for herself and Andrew through the infected zone.Their journey takes themg the way. Eventually, they are dropped off and given to a convoy with armed escorts who are to lead them by land to the US-Mexico border. As they are traveling, the convoy is attacked by the large aliens. As the tentacled creatures begin to demolish the other vehicles in the convoy, the escorts guarding Andrew and Samantha abandon them to try and bring down the attacking aliens.
The sounds of battle soon come to an end, and Andrew and Samantha are forced to hide in silence as the creatures surround and inspect the remaining vehicles. After Andrew shuts off the light in their van, the nearby aliens ignore them.
They instead destroy the remaining truck that had its headlights still on, indicating that light is of importance in some way to the aliens. When morning comes, it is evident that none of the guards had survived the ordeal, their bodies strewn across the jungle. Andrew salvages a pair of gas masks from two of the bodies before discovering the corpse of a slain female child. He regretfully documents what he sees before they move on. Andrew sees the body of the dead girl before he retrieves the gas masks. On finding the girl he is seen removing 2 camera lenses from his bag, but then removes a coat from further in the bag which he uses to cover the girl and onto which he places a yellow flower picked from the jungle. There is nothing in this scene of the film which shows him taking any photographs, thereby emphasising how his view of the 'issue' has changed since earlier in the film when he indicated that a photo of a dead girl would be worth $50,000. They make a day's worth of progress before they spend the night at the top of what appears to be an Aztec pyramid with the US border wall visible on the horizon. The next day, they arrive at the checkpoint nestled in a gap in the massive wall, but it appears to be unmanned. As they cross the abandoned checkpoint and explore suburban ghost towns, Andrew and Samantha realize the American border has been evacuated, and the aliens have advanced into the United States. After walking along an evacuation route, the two stumble across an abandoned gas station. Andrew calls the police and is informed they will be picked up. Andrew and Samantha phone their respective families. Andrew speaks with his son, becoming visibly emotional as he does so. As they finish their calls, a lone creature silently approaches the gas station from behind. Andrew fails to notice it as he lies on the concrete of the pumping station. It sends its tentacles into the store, setting off the typical door-chime. Samantha, thinking it is Andrew coming inside to join her, looks up smiling but quickly begins to scoot away across the floor, horrified. She hides behind a set of shelves as the two tentacles explore the inside of the store, getting dangerously close to her several times. They soon turn their focus to the TV that was displaying the news, pressing the tips of the appendages against the screen as pulses of light run up their lengths. Realizing the attraction toward the electrically-produced light, Samantha quickly unplugs the TV and the creature quickly loses interest in the store. The creature strides to the road beside the gas station as Samantha exits the store to join Andrew, where they both watch in amazement as a second alien appears and begins communicating with the first. Their communication appears to be more than simply vocal, as their tentacles interlace and pulse with light rhythmically. In this rare spectacle, the giant creatures no longer seem monstrous killers, but instead appear as gentle giants sharing a tender, beautiful moment as the two minuscule humans stare up at them in awe. However, as quickly as they came, the creatures part ways, leaving Samantha and Andrew alone together as they wait for the military to arrive. Watching them vanish into the night, Samantha tearfully declares, "I don't want to go home" and they share a brief kiss before they are interrupted by a military rescue convoy. As the convoy departs from the gas station, it is implied that the opening scene of the film showed what will happen after Andrew and Samantha are picked up, as one of the soldiers hums Wagner's "Ride of the Valkyries".