A sudden and rapid rise in solar activity afflicts Earth with blinding light and unbearable heat during the daytime.

Over time, the solar catastrophe becomes worse and society breaks down. Massive wildfires ravage the countryside, Visitors slaughter police and military patrols, cities are quarantined, hospitals are shut down, martial law is implemented, and anti-government riots erupt.

As temperatures are projected to continue rising and will soon reach lethal levels, the authorities (FEMA/EMERCOM) warn citizens to remain indoors during the day, causing them to adopt a nocturnal lifestyle. During the night, people begin encountering the mysterious and hostile "Visitors", who disguise themselves as humans and who reportedly emerge from underground and use their appearances to gain the trust of victims and kill them.

Visitors have certain physical differences that distinguish them from real humans, and the authorities try to keep the population informed about these signs through news broadcasts, some of them being: perfect white teeth or/and bleeding gums, dirty nails or oddly long fingers, irritated eyes or more than one pupil visible, no hair or fungus in the armpits and skin rashes.

It was a night like any other, the taskforce having trouble dealing with the visitor trying to devour them, and you were just another person, or visitor, knocking in to seek shelter, or a prey.