Demi Moore and Margaret Qualley try to share a body in The Substance trailer

We've known since it crawled up out of the primordial muck at Cannes earlier this year that Demi Moore, Margaret Qualley, and director Coralie Fargeat's new horror/satire The Substance was going to be an eye-catcher. And catch the eyes it indeed does, in its first full trailer, released on the internet today. And, yep, that's one of the more genuinely unsettling such bits of video content we've seen in a hot minute. (And not just because of the aggressive footage of Dennis Quaid shoving shrimp in his mouth…although that didn't hurt.)The film's premise seems to be a relatively simple sci-fi parable: After being fired from her job as a fitness celebrity for the egregious crime of turning 50, Moore's character Elisabeth is given a mysterious offer: Inject a bright green liquid into herself and…transform?…into a younger, "better" version of herself. That's Sue, played by Margaret Qualley, who apparently institutes some kind of time-sharing agreement with Elisabeth. The fact that the trailer gets more and more frantic and horrifying as it goes on—including one hell of a good shot of multiple irises and pupils breaking out inside a single human eye—suggests it might not end up going well.The Substance got strong reviews out of Cannes, with critics holding up Moore and Qualley's performances as especial highlights. It's certainly jumped to the top of our must-watch lists: This feels like the good, nasty kind of satire that knows exactly how to work its way under the audience's skins without letting a lot of worries like "subtlety" get in the way.The Substance debuts in theaters on September 20.