With more than 2.3 million people locked up, the U.S. has the highest incarceration rate in the world. One out of 100 American adults is behind bars – while a stunning one out of 32 is on probation, parole or in prison. These staggering numbers have created a thriving prison economy. The states and the federal government together spend roughly $74 billion a year on corrections, and nearly 800,000 people work in the business. On Tuesday, October 18th at 9PM ET/PT, CNBC’s one-hour documentary, “Billions Behind Bars: Inside America’s Prison Industry,” takes viewers behind the razor wire to investigate the profits and inner-workings of the multi-billion dollar corrections industry. From some of the poorest towns in America to some of the wealthiest investment firms on Wall Street, CNBC’s award-winning Senior Correspondent Scott Cohn travels the country to go inside the big and controversial business of prisons.