The first time Tony Ford played Dungeons & Dragons, he was a wiry Black kid who had never seen the inside of a prison. His mother, a police officer in Detroit, had quit the force and moved the family to West Texas. To Ford, it seemed like a different world. Strangers talked funny, and El Paso was half desert. But he could skateboard in all that open space, and he eventually befriended a nerdy white kid with a passion for Dungeons & Dragons. Ford fell in love with the role-playing game right away; it was complex and cerebral, a saga you could lose yourself in. And in the 1980s, everyone seemed to be playing it. The game has since become one of the most popular in the world, celebrated in nostalgic television shows and dramatized in movies. It is played in homes, at large conventions and even in prisons. When Ford, who is now on death row, first overheard the other men playing D.&D., they were engaged in a fast, high-octane version. The gamers were members of the Mexican Mafia, an ...