Border Patrol Agent Danika Morales has sworn to protect the southern borders of the U.S., but that oath has cost her dearly. She has paid a heavier price than most: her husband, Toby, was murdered two years ago trying to help the very immigrants Danika was responsible for sending back to Mexico-and his murder has never been solved. Now a string of attacks and arrests leads her to believe that someone from McAllen profits from sneaking undocumented...