Democracy for the Dead by Christopher Upham

Returning to the Vietnam,he knew as an American soldier, John Halliday searches for his older brother Nic, who disappeared during the war. Frustrated by arcane bureaucracies, his own PTSD inertia and two dead friends comically haunting him to join them, Halliday enlists the help of poet My Linh, a heroine of the "American War."

The two go on an epic VW bus journey crossing Vietnam, finding threadbare clues to Nic's disappearance and falling in love as they follow the clues south and then west to the old Ho Chi Minh Trail where both of them had served, shadowed by Dean Bolton, an American POW/MIA official under the guise of friendliness.

In the mountains of Cambodia, amidst their own turbulent relationship, Halliday and My Linh find answers to the mystery of Nic, finally accepting their own complicated roles in the war and afterwards, then facing an uncertain but hopeful future.