Medicins Sans Frontieres is also known as MSF, or Doctors Without Borders. They are the first ones to arrive when there's a war, an earthquake, an outbreak, or a famine. And increasingly, they are coming under attack. We spend a week inside one MSF hospital in South Sudan to find out what life is like for the people who do this work. Follow Kelly McEvers on Twitter @KellyMcEvers and Jason Beaubien @jasonbnpr. Email us at firstname.lastname@example.org.