GWEN IFILL:

The American-led coalition fighting the Islamic State group suffered a blow earlier today.

U.S. Central Command issued a statement saying that a Jordanian F-16 warplane crashed in Northern Syria. The jet's pilot was apprehended by Islamic State fighters. It's the first time a coalition service member has fallen into the jihadist group's hands.

Apart from its high-profile slayings of American journalists and foreign aid workers, brutality, and rapid land grabs in Iraq and Syria, very little is known about the organization also known as ISIS or ISIL.

Tonight, we hear from one Westerner who just spent 10 days inside Islamic State territory and lived to tell about it.

German author, activist, and former politician Jurgen Todenhofer did the seemingly impossible. After months of negotiating over Skype, he won a written security guarantee from Islamic State forces, granting safe passage through their territory, so he could research an upcoming book.

Todenhofer and his son entered through a border crossing in Turkey and were taken to the Syrian city of Raqqa, the Islamic State's seat of power, and then to the Iraqi city of Mosul. They were tightly supervised, but allowed to shoot interviews with Islamic State fighters and even prisoners.