Trust Me or Die

Cassie Yates drives out to a villa in the forest with her boyfriend and her closest friend. On the way she falls asleep and dreams that the two of them betray her, and that everyone in the group is swallowed by an enormous python. She wakes up and tells herself it was a nightmare. Then she finds a shed snakeskin, far too large for anything that should be in those woods, and the rest of the dream starts arriving in order. She warns the others. Nobody believes her, and they go on with the holiday while she works alone in the cellar, stocking it and getting it ready. The python comes. The people who run have to run for their lives, and the ones who listened to Cassie are shut in the cellar with her.