The video showed a man grinning into the camera, videochatting. Offscreen, there was a long boom and then the sound of gunfire. He paused, listening.The door slammed open and a bloodstained man staggered in."What's happening?" the first man shouted."They blew a hole in the courtyard wall."Another explosion came and the picture spun crazily and whited out. The ruined room came back into view, the webcam sideways on the floor, thick dust and chunks of masonry everywhere. The two men were nowhere to be seen.A pair of legs came into view from the hallway, baggy pants over worn leather sandals. They stopped in front of the camera. Then the video ended abruptly.For FBI Agent Samantha Calvert, this wasn't just another case. In fact, it wasn't her case at all. The man on the video was her brother, missing in Afghanistan.So when the Bureau says she's "too close to the matter" and "not objective," Sam reluctantly decides to ask for help from the last place she'd ever choose: A burned spy named Gault.