Two cross country gun-runners hit and kill a strange old woman with their disguised 18- wheeler. They soon figure out something strange about the woman as she has cursed them to drive across a dark, twisted reality of the world that they once knew.

I like it.

I actually like your better, thanks. I would change the DARK THINGS part, sounds too vague.

"When two gun-runners hit and kill an old gypsy, they become cursed into a twisted reality and must discover how to escape before the dark denizens devour them."

"When two gun-runners hit and kill an old gypsy, they become curse to a twisted reality and must discover how to escape before the dark things get them."

My attempt isn't perfect but I am trying to set the stakes, You tell us that they are trapped in a dark reality but don't tell us what the stakes are or what they must do. What are the dangers in the dark reality, what must the gun-runners do.

You have given us situation but until we know what they must do and what is standing in their way you don't have story.