'Cottonmouth (2020)' is a short horror film in which a woman becomes convinced someone - or something - is taking sips of her water while she sleeps. It's a solid piece focused more on atmosphere and tension building than anything else, which works well in creating a brooding affair that builds to a big finish. The finish in question isn't the best, but it does the job well enough. Overall, this is a pretty predictable effort. It's also well-made and engaging for its duration.