I remember seeing this movie somewhat recently, but I cannot remember where. It has two teens in it, a boy and a girl, who are not related, and an older man. They’re on a journey somewhere and every once in a while they are pursued by thick rolling smoke that some kind of beast travels in. The smoke is stopped by light, and they end up narrowly escaping most of the time. At one point the old man gets caught by the smoke and is seemingly eaten. I remember a scene later in the movie where they’re going through a valley and the smoke pours down the sides and surrounds them. At the end of the movie, the boy constructs this elaborate device to create a cage out of light and they end up trapping the beast that was in the smoke. I’m pretty sure they end up killing it but I am not sure.

I have tried searching elsewhere but all I get are results for The Mist, which I know it’s not. Thank you in advance for any help!