Reaction Time(2011)

Reaction Time is a survival thriller that traps a family inside their villa when an unnatural, flesh-burning fog engulfs the world outside. Cut off from all communication and dwindling supplies, they face an impossible situation—until a sound of breaking glass shatters their isolation. Someone has breached the fog and entered their home. As paranoia and desperation mount, the family must confront a terrifying question: is their mysterious intruder a savior or a threat? With no answers about what caused the fog and no way to escape, they're forced to rely on instinct and fear to survive. The film builds tension through claustrophobic dread and the creeping realization that not everyone dies in the fog—some live long enough to become something else.