Sitting on stairs of his house in a nondescript village near Uttarakhand's Roorkee, Nafiz Ahmed, was trying to make sense of the last few hours. On January 19, his 20-year-old son Mohammed Osama didn't return from his tuition classes. His phone was switched off and no one knew his whereabouts. Later that night, the Delhi Police called to say Osama was arrested for planning to blow up trains and trigger explosions at the Ardh-Kumbh mela.