The Broken Hallelujah by Wendy H. Adair

He’s been MIA since 1969, and his granddaughter is going to bring him home before her Gran’s mind forgets him.
The Broken Hallelujah is a national award-winning novel and #1 audiobook that travels in time over 50 years. Join Martin and his team in the steamy jungles of Vietnam and scheme with Robin in her Houston garden with her feisty Gran and the unlikely team she finds to bring him home. It takes a musical band of Vietnam Vets, a hunky photojournalist, some Vietnam refugees, and even her ex-husband to help uncover the conspiracy that left Martin buried in a field in Southeast Asia. Can Robin bring her grandfather home to the honor he deserves and heal her grandmother’s heart before her mind can no longer remember? It’s a race against the mental ravages of time and the bureaucracy of two former warring nations.