Into the Lawless Heart of Mexico. There are many ways to die in the Sierra Madre, a notorious nine-hundred-mile mountain range in northern Mexico where AK-47s are fetish objects, the law is almost non-existent and power lies in the hands of brutal drug mafias. Thousands of tons of opium and marijuana are produced there every year. Author Richard Grant thought it would be a good idea to travel the length of the Sierra Madre and write a book about it.