The killing that has been done and is being done is a crucial aspect of war and an integral part of the memories servicemen bring home with them. And yet, with few exceptions, it’s only rarely discussed in public and largely left to the veterans themselves to process, wrestle with, and carry.This is unfortunate because to understand what war is and what war does, it is necessary to understand what killing is and what killing does. In “The Kill Switch,” writer Phil Zabriskie, who covered both Iraq and Afghanistan for Time and other magazines, reconnects with two Marines and other veterans he met in Iraq and finds them ready to talk about it and willing to examine soberly and honestly what they’ve done and were asked to do. From boot camp through the initial invasion to the crucible of Ramadi, the siege of Fallujah, and beyond, they recount firefights, ambushes, suicide car bombers, hand-to-hand combat, and the life and death decisions they made about Saddam’s soldiers, battle-hardened insurgents, and people, even children, who were in the wrong place at the wrong time. Unflinching and as important today as it was at the height of these wars, “The Kill Switch” will stay with you long after you’re finished, just as the wars these men fought—and the killing they did—have stayed with them. Phil Zabriskie is a New York-based writer who spent many years working across Asia and the Middle East. He reported extensively on America’s wars in Afghanistan and Iraq for Time magazine and has also written about conflict and its impact on the people who live through it for National Geographic, Fortune, the Washington Post Magazine, and other publications. Cover design by Kristen Radtke.