PLOT.
After a NASA deep-space probe crash lands in Mexico, extraterrestrial life forms spread throughout the Mexico–United States border region, leading to the quarantine of the northern half of Mexico. US and Mexican troops battle to contain the creatures, while a wall stretching along the American border ostensibly keeps the US protected.
American photojournalist Andrew Kaulder (Scoot McNairy) receives a call from his employer, who tasks Andrew with finding his daughter, Samantha Wynden (Whitney Able), and escorting her back to the US. Andrew locates Samantha in a Mexican hospital and the pair board a train, until learning the tracks ahead have been damaged. They discover that if they do not leave the country within a few days, sea and air travel will be blocked for six months. Andrew and Samantha decide to hitchhike their way to the border.
Andrew buys Samantha an expensive ferry ticket for the next morning. After enjoying the local nightlife together, Andrew has sex with a local girl who steals their passports. Unable to board the ferry, Samantha is forced to barter her engagement ring for passage through the quarantine zone.They travel by riverboat until being transferred to a group of armed escorts who are to lead them overland to the Mexico–US border. The convoy is attacked by the creatures. Andrew and Samantha escape, but none of the guards survive. Continuing on, they discover the bodies of dead travellers and bond at the top of an ancient pyramid in sight of the US border wall. By the time they reach the border, the creatures have broken through. They travel through a ghost town in Texas, find an abandoned gas station with power and call the army for help.
While waiting for help to arrive, they make phone calls to their respective families. A lone creature silently approaches the station. Hiding, Samantha observes several tentacles exploring the inside of the store, seemingly soaking up a television's light. Samantha quickly unplugs the television and the creature loses interest. Another creature appears, and they communicate with one another and mate via light impulses. The creatures leave as the military arrives. Samantha and Andrew kiss before they are rushed into different vehicles. The convoy is quickly attacked by monsters, and the military fires an airstrike at them.

Editing and effects.

Every night after shooting, editor Colin Goudie and his assistant Justin Hall would download the footage so the memory sticks could be cleared and ready for the next day. While new footage was being captured, the previously filmed footage was edited at the production team's hotel. After filming concluded, the crew had over 100 hours of footage. The original cut was over four hours long but was trimmed to 94 minutes after eight months of editing. Edwards originally had the ending of the film both at the beginning and the end. He and the film's producers disagreed about the placement, so he decided to put the chronlogical ending of the film at the beginning and end the film immediately after Andrew and Samantha kiss.
Edwards created the special effects himself using off-the-shelf Adobe software, ZBrush, and Autodesk 3ds Max. He had five months to create all 250 visual effects shots, a process he undertook in his bedroom. He produced two shots a day until he reached the first creature shot, when "suddenly two months went by and [he] still hadn't finished a single creature shot"; Edwards stated that the creatures' visual effects were the most challenging element of production. Due to time constraints, the sound effects had to be produced before the special effects.