The Natchez Trace National Parkway stretches 444 miles from Nashville to Natchez, the oldest town on the Mississippi River. It's the perfect road for a relaxed pleasure drive. Unfortunately for park ranger Luke Fereday, lately it's being used to move drugs. Sent to Natchez to infiltrate the organization at the center of the drug ring, Luke arrives too late to a stakeout and discovers the body of his friend, park ranger John Danvers.

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.

When one Coast Guard officer is found dead and another goes missing, Coast Guard Investigative Service special agent Finn Walker faces his most dangerous crime yet. His only clues are what little evidence remains aboard the dead officer's boat, and the direction the clues point to will test Finn and the Guard to their limits. When investigative reporter - and Finn's boss's sister - Gabby Rowley arrives, her unrelenting questions complicate an already volatile situation. Now that she's back, the tug on Finn's heart is strong.

Detective Londyn Steele is thrown into the deep end when she’s assigned to find an abducted socialite. Problem is, her family’s company, Steele Guardians, was supposed to protect the family matriarch at her 80th birthday party when she disappeared, and Londyn fears her investigation will expose problems in her family’s company and bring them down. Especially when County Detective Nate Ryder declares jurisdiction over the scene and Londyn must take a back seat in one of the most important cases she’s ever investigated.

Former pararescue jumper Orion Starr is haunted by the memory of a rescue gone wrong. He may be living alone in Alaska now, but the pain of his failure - and his injuries - has followed him there from Afghanistan. He has no desire to join Hamilton Jones' elite rescue team, but he also can't shirk his duty when the call comes in to rescue three lost climbers on Denali. Former CIA profiler and psychiatrist Jenny Calhoun's yearly extreme challenge with her best friends is her only escape from the guilt that has sunk its claws into her.