40 years ago, the Iranian hostage crisis gripped the world, with details unfolding nightly on television. But one story remains untold. Desperate to get their message out, the hostage takers invited 50 ordinary Americans to visit Iran. For the Americans, this high-risk trip held the tantalising possibility of securing the release of hostages. What transpired was a journey quite unlike any of them had planned. Using archive of the visit and fresh interviews with former Iranian hostage takers in Iran and their American visitors, we hear about their hopes and misgivings at the time and their reflections 40 years on. Part of the BBC's Crossing Divides season.