S2E79 - The Seventh Door and the Child Who Opened It

Luna stands before the seventh door in the attic, labeled with her own name, as the Hollow's heartbeat pulses beneath her. She opens it and steps into a nursery from 1973, where a version of her mother waits with a cassette titled 'The Child Who Opened the Door.' The tape reveals that the child has been inside Luna all along, waiting to be born. Luna must let the child emerge or be consumed by the Hollow. As she decides, the heartbeat in her chest splits again, and she feels a cold hand pressing from inside her ribs. The episode...