After an accidental shooting of a teen during a tense standoff, FBI Hostage Rescue Team member Mark Sanders is sent to St. Louis to work as a field agent and get his bearings while the bad press settles. Just weeks away from returning to Quantico, Mark has a chance encounter with his first love, Emily Lawson. But their reunion is cut short by a sniper. Now Mark must find the shooter before he strikes again. But what is his motive --- and who was his intended target? Can Mark put the pieces together, keep Emily safe, and rekindle a long-dead relationship at the same time?