Blood

In a 2023 interview with Film International, Brad Anderson spoke about the origin of the setting and the importance of ambiguity in horror stories: "In the original script there was a cave that the kids found as opposed to a dry lake with a tree and the tree was something I brought into it partly because we shot the movie in Winnipeg Canada where there are no caves but I also just like the idea of an old tree being somehow representative of whatever the potentially supernatural element is. There's a moment when she looks and sees bats going into the tree and you could think that maybe there's something in there, in the same way that bats were apparently the reason that COVID-19 kicked in. There are little references like that but image of a single tree in this sort of muddy little swamp to me was really creepy and intriguing and asks a lot of questions. There are little subtle things like there's a moment in the beginning when you see a picture from the people who lived in this house like a hundred years ago and it's the same tree but that tree is in blossom and alive, so it's died over the years and maybe it's become this kind of place where bad stuff lives. I would like to keep a little mystery in the story. I think the best kind of horror lives in between spots and it's not overly explained because if you over explain the monster then the monster loses its power to scare you. We did at one point flirted with the idea of seeing something in there like seeing a humanoid shape but I just felt in the end it's more interesting to let the audience ask that question whether they have an answer to it or not. There had to be a kind of reason why this kid gets infected, some sort of explanation, but you don't want to go too far with that, at least in my mind. I think it's better to have a little ambiguity in the story."