"Mercy River" by Glen Erik Hamilton (Van Shaw novels, book 4)

When his friend Leo Pak is arrested on suspicion of murder and armed robbery, Van Shaw journeys to the remote Oregon town of Mercy River to help his fellow Ranger. Van learns that his troubled friend had planned to join a raucous three-day party that’s attended by hundreds of former and active Rangers. The event is the central celebration of a growing support network called the Rally. But he soon discovers there’s much more going on in Mercy River.

The murder victim—the owner of a local gun shop where Leo worked part-time—was dealing in stolen heroin-grade opiates. Worse, the town has a dark history that includes white supremacists who are threatening to turn Mercy River into their private enclave. The cops have damning evidence linking Leo to the murder, and Van knows that backwaters like Mercy River are notorious for protecting their own. His quest to clear Leo’s name will stir up old grudges and dark secrets beneath the surface of this fearful small town, pit his criminal instincts against his loyalties to his brothers-in-arms, and force him to question his own belief in putting justice above the letter of the law.