The Covenant of the Flame

In the Amazon basin, the widow of a rubber-tree tapper who was assassinated for opposing destruction of the rain forest receives a gruesome gift the head of the financier who ordered her husband's death. In Australia, a tanker captain responsible for a massive oil spill is blown to pieces and top oil executives are drowned or poisoned. Soon, a young investigative journalist has discovered the shocking conspiracy and becomes caught in a deadly war between two brutal and desperate factions, with nothing less than the future of the planet at stake.
"Spain, 1391. Archdeacon Ferran Martinez, driven to excess by his fervent Catholicism, preached increasingly inflammatory sermons against all heretics. On 15 March, Ash Wednesday, his charismatic hate-filled oratory aroused his parishioners to such a frenzy that they stormed from his church toward the Jewish quarter of Seville. If not for the orderly minded civil authorities, a massacre might have ensued. Instead two leaders of the mob were seized and scourged. But their punishment, far from being a discouragement to fellow bigots, made the leaders martyrs and fueled the fires of their followers' hate. Anti-heretical fury spread from Seville to neighboring cities and finally throughout Spain with the terrible consequence that during the summer of 1391 an estimated 10,000 disbelievers were executed, most by beatings and stonings.  Several, though, were put to the torch."