“Whenever I tried to invent a character or a situation, I felt a stab of guilt. I could hear my teacher’s quavering voice saying, Write what you know! Why had she insisted on this so vociferously?” Writing class mantras are easy to impart but they are also easily misinterpreted. A.X. Ahmad, author of The Last Taxi Ride and The Caretaker, learns this truth the hard way as he tries to become a writer following a personal upheaval. Pair with Ahmad’s Millions essay on “The Thriller, Reinvented.”