A couple, Tom and Lucy, had just started dating two weeks ago, and she agreed to go with him to a music festival in Ireland. The movie actually starts with a shot of the countryside while his voicemail plays in the background. He tells her to invite her friends, and they'll all go camping.

So we open up to a snowy wasteland in 2045. The world has been covered in a state of perpetual deep, deep snow. It's been snowing for a long time, and the surviving members of humanity are hunkered down in underground bunkers. It is similar to George Romero's underrated Day of the Dead, but instead of zombies, think a shit ton of snow.