The author, a U.S. Navy SEAL, writes about his canine partner, Cairo, who was trained to enter war zones, detect explosives, and attack enemies. Chronicles their two deployments in Afghanistan, and their numerous missions including the 2011 secret mission to capture Osama bin Laden. Details their deep bond, their life together after Cairo retired, and the role Cairo played in helping the author heal after being wounded by a grenade on a mission.