Rusty Young was backpacking in South America when he heard about Thomas McFadden, a convicted English drug trafficker who ran tours inside Bolivia's notorious San Pedro prison. Intrigued, the twenty-something Australian law graduate travelled to La Paz and joined one of Thomas's illegal tours. What followed took both men by surprise: they formed a strong and instant friendship and then became partners in an attempt to record Thomas's experiences in the jail.

Marching Powder is a shocking, sometimes darkly comic account of the life in San Pedro. In this bizarre prison, inmates are expected to buy their cells from real estate agents. Others run shops and restaurants, and hundreds of women and children live with imprisoned family members. It is a place where corrupt politicians and drug lords live in luxury apartments while the poorest prisoners are subjected to squalor and deprivation. Violence and crime are never far away, and sections of San Pedro that echo with the sound of children by day, house some of Bolivia's busiest cocaine laboratories by night.

Yet amid the corruption, brutality and the daily struggle for survival, Marching Powder is also the tale of an unlikely friendship, forged in the oddest of circumstances, between a drug smuggler and a lawyer. It is the story of one of the strangest places on earth, where horror is leavened by humour and where cruelty lives side by side with compassion.