And what, Gul'Dan, must we give in return?

A teenage Austrian girl who fled to Syria along with her friend is believed to have been beaten to death after being caught trying to flee the ISIS stronghold of Raqqa.

Samra Kesinovic, 17, and her friend Sabina Selimovic became 'poster girls' for ISIS after they arrived in Syria in April 2014.

I don't know what it is about islamist jihadi ideology that appeals to young people from liberal, secular, western backgrounds.

Maybe it's the quest for a strong identity in a world that seems to offer only bland, generic identities.

Maybe it's the dangerous lure of the exotic and the primitive in a world that seems almost too civilized, too comfortable, too safe.

Maybe it's admiration of the ruthless power of the jihadis, or fear of that power, or the desire to put one's money on "the strong horse".

Or maybe it's even simpler than that: the promise of untold wealth and power tomorrow if one will only swear fealty to the Muslim warriors today.

These girls figured out more than a year ago that they had made a terrible mistake. But it was already too late, and there was no turning back.