Brian Viner 
No Fifth Horseman [EPUB ebook] 

Marty Rebel, insurance investigator-turned-assassin-hunter, is intent on bringing ex-Spetsnatz soldier-turned-assassin, Captain Lars Gottard, aka Pelops, to justice for the slaying of people close to him. With his newspaper reporter girl friend, Dixie Montcliffe, his long-time friend, retired detective chief superintendent, Colin Robbin and the father of one of the assassin’s female victims, retired Air Chief Marshal Edgar Thompson, he embarks on a sea voyage to the Democratic Republic of Congo in pursuit of his quarry. His team, with all the necessary transport and equipment to make the journey in the Karangabe Desert, is making the journey on a North sea trawler skippered by old sea-dog, Ethan J. Entwistle. He is joined by his old Domino mate, ex-special forces man, Weeny, with one of the EU organisation’s helicopters.
Pelops and his paymaster, Cesar Quesada, a Colombian drug-lord, are involved in the process of mining uranium ore in the vastness of the Karangabe Desert, with which Quesada hopes to bargain for political power. The German’s role is to provide protection, including the supervision of a squad of armed mercenaries enlisted as protection against marauding rebels.
Montague Scott, scientific genius, engineer and brother of another of Pelops’ victims, also has plans to avenge Pelops’ murder of his brother. Assisted by his personal aide, Dimitri, and a seafarer, Alistair Cameron, he follows Marty in a machine of futuristic design, equipped with weaponry that would be the envy of his contemporaries in the arms industry.
Congolese rebel commander, self appointed Brigadier Standi Nyando, has designs on the minerals being harvested by the foreigners in the desert, though he is not aware of the precise nature of it, merely any value it might have, and the kudos its seizure will bring him.
The three factions meet head on in the desert, with varying degrees of advantage to one group and then another; with Marty and his team managing to survive, only to have to resume pursuit of Pelops and Quesada back north, towards colder waters, and…