For Green Beret Travis Chapman, special operations and covert missions are his life. When his country calls, he reports without question. Until now. Until he’s tasked with protecting a woman he’d once loved and sent him packing. He’d rather go AWOL than spend time with civilian researcher Claire Reed. Even when he learns that her vital research project is stolen, he thinks twice about seeing her again.

EMT Freya Olson has lost her faith, but not her drive to save those who need her help. When the past that her family left behind after her mother's death shows up in Benson, Freya lands on the target list as well. But things aren't what they seem, and Freya’s loyalty will be pushed to the limit.

Mercy Brennan followed in her father's footsteps in a law enforcement career, but she has no interest in any other connection to him. A US Marshal in St. Louis, Missouri, she's assigned to a joint task force with the St. Louis PD that puts her back into contact with her father and in the sights of St. Louis's most powerful gang. When the gang has reason to believe Mercy has possession of some highly sensitive and incriminating information, her boss assigns Mark St. Laurent - a Deputy US Marshal and Mercy's ex-boyfriend - to get her out of town.

Kaely Quinn's talents as an FBI behavior analyst are impossible to ignore, no matter how unorthodox her methods. But when a reporter outs her as the daughter of an infamous serial killer, she's demoted to field agent and transferred to St. Louis. When the same reporter who ruined her career claims to have received an anonymous poem predicting a string of murders, ending with Kaely's, the reporter's ulterior motives bring his claim into question. But when a body is found that fits the poem's predictions, the threat is undeniable.

Detective James Holton has been honorably discharged from the Army Criminal Investigation Division due to wounds sustained when an IED blew up near him. Now with the Lake City Police Department, he's rooming with his good buddy and partner, Cole, while he figures out his family dynamics. Physician Assistant Lainie Jackson is eighteen months out from an attempted murder perpetrated by her ex, which ended when she managed to grab the weapon and shoot him. When he appears to have survived and is back to finish the job he started, Lainie insists it's not possible.