So Sweet Justice

A romance hatched in 1968 in war-torn Vietnam comes to a violent end when enemy guerrillas attack the U. S. Naval Hospital at Da Nang, taking the life of Navy nurse Angela Robbins and stealing her opal engagement ring, given to her by Marine pilot Warner Nichols in contemplation of marriage.
Time and the War continue and Warner's private focus remains on the missing ring and the identity of the perpetrator. His life is almost destroyed except for Vic Tobias, his wingman who monitors his every move in the air, and for British nurse Jennifer Hartness, who cares for him as she positions herself in Angela's shoes.
It is only after Warner returns to the States and is later re-assigned to Vietnam that a clue surfaces, renewing his vow to unravel the mystery.