Dr. Willa Watters is a prominent child psychologist at the height of her career. But when a viral video of a disastrous television interview puts her reputation on the line, Willa retreats to Broken Bayou, the town where she spent most of her childhood summers. There she visits her aunts’ old house and discovers some of her unstable mother’s belongings still languishing in the attic—dusty mementos harboring secrets of her harrowing past. Willa’s hopes for a respite are quickly crushed, not only by what she finds in that attic but also by what’s been found in the bayou.

FBI special agent Mercy Kilpatrick has been waiting her whole life for disaster to strike. A prepper since childhood, Mercy grew up living off the land — and off the grid — in rural Eagle’s Nest, Oregon. Until a shocking tragedy tore her family apart and forced her to leave home. Now a predator known as the cave man is targeting the survivalists in her hometown, murdering them in their homes, stealing huge numbers of weapons, and creating federal suspicion of a possible domestic terrorism event.

Carmen Sanchez is a tough Homeland Security agent who plays by the rules. But when her sister is attacked, revealing a connection to a series of murders across Southern California, she realizes a conventional investigation will not be enough to stop the ruthless perpetrator. With nowhere else to turn, Sanchez enlists the aid of Professor Jake Heron, a brilliant and quirky private security expert who, unlike Sanchez, believes rules are merely suggestions. The two have a troubled past, but he owes her a favor and she’s cashing in.

After his wife and two children are killed in a car crash, Ryan Tapia starts a new life in Maine. But his first case there is a puzzling oddball—the corpse of a fisherman washes up on federal land, while the man's boat drifts into waters that are part of an Indian reservation.

When Anna Hartley’s husband, Henry, calls her with a terrible, guilty confession, she can’t believe what she hears. It has to be a bad joke—the mild, predictable artist she married would never hurt a fly, let alone commit murder. But her confusion turns to horror when police find his body washed up on the banks of the Rio Grande.