The lush peaks of Iraqi Kurdistan are irresistible to a certain breed of bold backpacker: They’re exotic, beautiful, and way off the beaten track. But when three young Americans were arrested by Iranian border guards last July after straying too far down a trail, the costs of adventure travel got a lot higher. As the hikers languished in their cells, Joshua Hammer decided to find out how they got into this mess - and what it would take to get them out.