Sarah and Mark are traveling through rural Ireland when car trouble strikes. The couple must head out on foot to find any sign of civilization. Eventually they come upon a lonely house – but the man inside is wounded, and when they try to help him, he attacks. Sarah and Mark manage to escape but soon they are confronted by something even worse.

A sinister being has awakened from a thousand-year sleep and it has set its sights on the stranded young couple. Deep within the dark bog, the two are faced with an unimaginable evil, but they soon realize that there may be one thing that can stop the creature: light. As the sun sets and light sources dwindle, the creature becomes more powerful, and Sarah and Mark find themselves in a fight for their lives where a gas lamp or even just the illumination of a single match may be the only thing that can save them.