A shut-in teenager moves into a run-down apartment building right as people around the world start turning into monsters shaped by their deepest desires. I came for the creature design — which is genuinely excellent, all practical weight and wrongness — and stayed for something quieter: a building full of strangers deciding, floor by floor, whether to stay human. Song Kang carries the lead role with a kind of hollowed-out stillness that works better than heroics would, and Lee Jin-wook shows up and immediately makes every scene tenser. The best stretches are the ones where nothing attacks at all, and the residents just have to negotiate food, doors and trust. It does sprawl, and not every subplot lands with the same force. But as a horror series built on the idea that the monster you become says what you wanted most, it stuck with me longer than I expected.