"The Quest" by Nelson DeMille
Nelson DeMille, is the author of such best-sellers as: Night Fall, Plum Island, The Gate House, Wild Fire, The Gold Coast, and The General's Daughter. Now, his first book, originally released as a mass-market paperback in 1975, The Quest, has now been entirely rewritten and expanded with new characters and a new ending.
From the war-torn jungles of Ethiopia to the locked archives of the Vatican, an unlikely trio who are bound by love and a deathbed promise begin a search for the holiest of relics. Their quest begins when they encounter a dying priest in the jungle who tells them that the Holy Grail is hidden nearby.