On a desolate, Midwestern county road, a bound man crawls towards a remote postal box, managing to slide a blood-stained plea-for-help message into the slot before a panicking figure closes in behind him. The note makes its way to the county post office and onto the desk of Jasper, a seasoned and skilled "dead letter" investigator, responsible for investigating lost mail and returning it to its sender. As he investigates further, Jasper meets Trent, a strange yet unassuming man who has taken up residence at the men's home where Jasper lives. When Trent unexpectedly shows up at Jasper's office, it becomes clear he has a vested interest in the note, and will stop at nothing to retrieve it....

The four brothers of the anti-drug team—Tai Hua, Lao Mi, A Feng, and A Tang—once participated in a mission to capture the drug lord "Old Dad." Before the operation, they handed in their phones to prevent eavesdropping. However, due to a corrupt cop's betrayal, they fell into a trap. A Feng was killed, Inspector Lu also lost his life, and A Tang disappeared, leaving tension between Tai Hua and Lao Mi. To uncover the truth and destroy the drug cartel, the two went their separate ways, struggling between loyalty and betrayal, justice and evil. Amid internal conflicts, the battle for justice faces an uncertain fate.

Leaphorn and Chee seek justice in the mysterious disappearance of a Navajo boy, while an FBI agent looks into a case linked to Leaphorn's recent past. Meanwhile, Manuelito unearths a conspiracy on the border with far-reaching implications.