The worst Marine-on-Marine friendly fire incident in modern history happened during the war in Iraq. In Spring 2004, an explosion rocked a schoolhouse in the city of Fallujah. It left three dead and a dozen wounded. But you won't read about it in the history books. In fact, the event seems to have been scrubbed from the official record. So, why were the families of the deceased lied to? Why did the reports mysteriously disappear? And why do survivors still have to wonder about what happened that day? Today, we begin to uncover the truth. We bring you the first episode of Taking Cover, an investigative series from NPR's Embedded podcast. It's a story of betrayal, brotherhood and what's owed to families, the wounded, and the American public.