The Mongoose

In the final days of the Vietnam War, Peter Jensen, a young CIA data analyst was found with his throat slit behind a brothel in the town of Xuan Loc just thirty miles northeast Saigon. He was executed because of what he had witnessed, the killing of a U.S. Senator who was looking into CIA corruption and drug trafficking. Just before his death, Jensen writes an encrypted letter explaining what he has seen. Before he can deliver it, his killer, a beautiful, cunning, and manipulative woman who will destroy anyone who gets in her way, is at his door, and he hides the letter.
By a series of chance events, Jensen's letter ends up in the hands of Shawn Harris, a tough, hard-drinking womanizer and a MAC-V-SOG Green Beret. Through some detective work, Harris knows what has fallen into his hands and he suspects who the Jensen's killer may be. But the war has ended, and his number one priority is to find and kill his stepfather for the murder of his mother.
The letter will languish in Shawn's Army duffel bag for the next thirty years until an event brings it to the surface: the Assassination of the President of the United States. Shawn, now living in Phuket, Thailand, recognizes Jensen's killer as the new President, and he sets out to decode the encrypted letter and bring Jensen's killer to justice.
With the advent of climate change and the push for alternative energy, a powerful man has taken steps to slow the progress and ensure that oil will never be replaced. He is a man of unlimited resources. He has hired a group of skilled technicians and mercenaries to infiltrate alternative energy research facilities to steal research material or, through threats of violence to family members and intimidation, stop the research altogether. And if necessary, kill anyone that stands in his way, even to the point of assassination of world leaders and placing his puppets in power to do his bidding. Through his spies in the NSA and CIA, this man has been informed of the existence of Jensen's letter, and if it sees the light of day, it will destroy everything that he has tirelessly worked for. Now, he must send his mercenaries to recover it and kill anyone who has knowledge of its existence to protect the woman he has placed in power.