John Britt 
The Third Wire [EPUB ebook] 

The Third Wire is the last chapter of the Dan Roberts trilogy. The novels are independent works, but the author recommends reading in chronological order.
In The Spad Driver Roberts, a young Naval Aviator deals with the realities of the Vietnam War and felony aboard an aircraft carrier.
Helens Challenge finds Roberts in middle age confronted by a retired reporter who had witnessed the unpunished crime Roberts committed.
The Third Wire Roberts wife has died. Elderly and alone, he has lost the will to live. Then a powerful nemesis blackmails him. He reluctantly agrees to investigate the disappearance of a former associate. He soon uncovers layers of deceit, and experiences a final redemption.