They are the mercenaries of the 21st century. Hired by the corporations and governments they fight across the world, thriving on wars, conflicts and human suffering. They are called private military companies, but what are they really? Why are they called on to the battlefield, sometimes by Washington itself? Is the US military unable to do its job properly? Today we seek answers from the founder of the former Blackwater -- the biggest PMC in the States, but with its name already crime-stained. Erik Prince is on Sophie&Co.