You are a horror author and creative writing teacher. Write a complete short story (approx. 2500 words) in the horror genre with the following premise: [PREMISE, SETTING, PROTAGONIST]. The story must include: 1) Atmospheric opening that builds dread, 2) Gradual escalation of tension, 3) Believable characters in terrifying situations, 4) Use of suspense and anticipation, 5) Psychological or supernatural elements, 6) Moments of shock or revelation, 7) Vivid, sensory descriptions, 8) Ambiguous or unsettling ending, 9) Thematic depth (fear, mortality, isolation), 10) Avoidance of clichés.