“We’ll be watching,” the sergeant said, pointing at a video monitor inside Camp Echo’s guard booth. “For your protection.”

In 2004, attorney Joshua Colangelo-Bryan arrived at Guantanamo Bay to meet Jaber Mohammed, one of six Bahraini detainees his firm had agreed to represent. Colangelo-Bryan had heard these men were “among the most dangerous, best-trained, vicious killers on the face of the earth,” as Secretary of Defense Donald Rumsfeld put it. Colangelo-Bryan didn’t buy the rhetoric, but did find himself wondering if he was about to meet a killer.

Far from being threatening, though, Mohammed welcomed Colangelo-Bryan, even as his ankle was shackled to the floor. Why was Mohammed there? Was he guilty of a crime? These were among the questions Colangelo-Bryan had to answer. Surprisingly, the two spoke for hours about their lives. Mohammed also detailed the inhumane conditions at the prison, including abuse by guards and solitary confinement.

A friendship grew over time, as Colangelo-Bryan worked to bring justice to Mohammed. The Bush administration claimed any “enemy combatant” could be held in Guantanamo forever without a trial, and it became clear that litigation was unlikely to free the Bahrainis. And so, as Mohammed lost hope, Colangelo-Bryan devised a plan to leverage the media and pressure the Bahraini government to negotiate for the release of its citizens. Colangelo-Bryan’s long fight for the Bahrainis was ultimately successful, and, in 2007, after several suicide attempts, Mohammed was freed.

Through the Gates of Hell is a powerful account of an unlikely friendship and what it takes to fight for human rights in the post–9/11 era.