On 21 August 2015, Ayoub al-Khazzani boarded a train in Brussels bound for Paris. We now know that he was an ISIS terrorist. Khazzani’s mission was clear: he had an AK-47, a pistol, a box cutter, and enough ammunition to obliterate the 554 passengers on the crowded train. But as he began to execute his plan, he encountered an unstoppable line of defence: three American friends.

The 15:17 to Paris is a gripping account of the foiled attack by the three men who lived it—Anthony Sadler, Alek Skarlatos and Spencer Stone. It is also the story of what compelled three lifelong friends to run towards danger instead of from it—towards humanity, not away from terror.