Two enemies stand face to face, observing each other. In turn, each of them reveals the reasons behind their decision to go to war. How they came to take up arms to defend their values, their family, their tribe, or their faith—following in the footsteps of their parents and forebears who did the same. What exactly do we know about these combatants? What do we really understand about the motives that push human beings to engage in combat—putting themselves at risk of both being killed and of becoming killers themselves? And why continue to fight over the course of several generations? What does freedom look like for these warriors? What is their future? Israel and Palestine, Congo, El Salvador, North and South Korea, South Sudan, Kashmir—of all the conflicts in the world today, these seem to be the ones that most dramatically represent the improbability of those on opposite sides ever identifying with one another.