Behind Bars: The World's Toughest Prisons 2016 Trailer

These are some of the toughest prisons in the world. Prisons so tough, even gang bosses and killers learn the meaning of fear. Across four continents, six different prisons, the series takes us beyond the gates, walls, barred windows and cells into an unknown world, a world we know exists, but a world nobody wants to think about.