For Caleb and Sophie, apartment 404 was a refuge. Inside jokes, comfortable routines, vague plans for the future. A little universe where the chaos of the outside world stayed outside the door.But refuges have walls. And sometimes, walls start to breathe.First, it's the details. A dripping faucet that sounds like a countdown. Lights flickering in an almost intentional pattern. Sounds that shouldn't be there-and shouldn't make sense. Then the neighbors. Anonymous figures in the elevator who suddenly feel like echoes of themselves. Something woke up in the building. Something that had been growing in the foundations like a silent infection.And now, Caleb and Sophie are trapped. In a building that stopped being a home and became a vertical trap. Every door could hide the end of sanity. Every hallway is a concrete maze where logic doesn't apply.Where do you run when the terror isn't trying to get in, but waking up from inside the walls?