I have never believed in ghost stories. I studied science. I believe in reason, probability, and cause and effect. Yet once in my life I witnessed something so strange that even today I struggle to explain it. It began with an inexplicable journey across half of India—and ended with a moment in my own house that felt deeply supernatural. It happened during Diwali in my third year at IIT. Diwali was usually not a holiday for us, but that year our exams had just finished and there was a short break. Many students were leaving for home. I had no such plan. My home was on the other side of the country, and traveling that far as a student with little money was not easy. Then my friend Kailash from Kanpur casually asked me, “Why don’t you come with me to Kanpur? From there you can go to Patna.” I had never attempted something like that—cutting across half of India just to reach home for Diwali. But for reasons I could not explain, I agreed almost immediately. Looking back, it felt less...