First Frost: A Longmire Mystery by Craig Johnson

It seems like you're describing a synopsis for a novel in the Longmire series by Craig Johnson. In this installment, the story alternates between two timelines involving Walt Longmire and his friend Henry Standing Bear.

In the summer of 1964, Walt and Henry, recent college graduates, enlist to serve in the Vietnam War. Before reporting for duty, they find themselves in California where they witness a cargo boat capsizing during a storm. Their attempt to assist reveals that the boat was carrying valuable contraband, setting off a chain of events that puts them on a collision course with trouble.

Meanwhile, in the present day, Walt Longmire is dealing with the aftermath of events from "The Longmire Defense". Facing powerful adversaries and legal consequences, Walt must navigate a complex web of conflicts and decisions. As the story unfolds across these two timelines, Craig Johnson explores themes of justice, loyalty, and the consequences of one's actions.

The novel promises a gripping narrative that weaves together past and present, showcasing Walt Longmire's character at pivotal moments in his life, balancing between moral dilemmas and the relentless pursuit of truth and justice.