When the narrator left for a short work trip, she felt confident leaving her husband, Mark, in charge of their baby, Emma, for two nights. Expecting only small issues like a skipped nap or a messy meal, she decided to check the baby monitor out of habit before bed. What appeared on the screen left her frozen — an unfamiliar woman was in the nursery, gently rocking Emma beneath the soft glow of the nightlight.

The woman looked older, with silver hair and a calm, nurturing demeanor. Emma seemed content, not frightened. Though the stranger’s actions were tender, the realization that someone unknown was with her baby filled the narrator with terror. Heart racing, she called Mark immediately. His alarmed reaction made it clear he had no idea who the woman was either. Something was terribly wrong.