A hardened woman, Em, and her fiancé, Hazel, a lively artisan, live together in isolation after the collapse of modern society. When Hazel begins to experience the transmutative effects of an unknown infection, Em begins a secret effort to cure her, going to great lengths to slow the infection and hold on to the life they know. As these attempts begin to put a strain on their relationship and fail to stop Hazel’s transformation, Em is forced to confront the inevitable: Hazel will change, and Em can either change with her or let her go.