In the aftermath of a personal tragedy, Harper (Jessie Buckley) retreats alone to the beautiful English countryside, hoping to have found a place to heal. But someone or something from the surrounding woods appears to be stalking her. What begins as simmering dread becomes a fully-formed nightmare, inhabited by her darkest memories and fears in visionary filmmaker Alex Garland's (Ex Machina, Annihilation) feverish, shape-shifting horror film.