Source
Creatures, known as Reapers, have emerged from the depths of the planet with the intention of exterminating the human species.
The peculiarity of these creatures is that they seem unable to survive at altitudes above 8,000 feet.
The story takes place in a shelter, which also functions as a settlement, located at 8,460 feet in the Rocky Mountains of Colorado.
The plot begins three years after the appearance of the Reapers, in a world where the population has been reduced by 95%.
Source
The main characters include Will, played by Anthony Mackie, a father who has lost his wife and is caring for his young son, Hunter, who suffers from respiratory problems.
There is also Katie, a brave and determined young woman, and Nina, played by Morena Baccarin, a scientist who studies the creatures and who, it seems, has a link to the death of Will's wife.
The situation is complicated when Hunter runs out of filters for the machine that helps him breathe, forcing Will to embark on a dangerous journey.
This journey will take him across the safety line, as the hospital where the filters are located is 2,000 feet below their safe haven.
Although Nina initially has no intention of accompanying him due to the suicidal nature of the mission, the story could not proceed without her involvement, and Katie also joins the expedition.
The group has a compass that becomes erratic when the Reapers are within half a mile, as these creatures possess a magnetic field of their own that seems to be more powerful than Earth's.
Most importantly, the film manages to hold the viewer's interest, despite its lack of originality and entertainment, as it resembles other familiar films in the genre.