Oligarkh
(Tycoon - A New Russian)
(2002)

Plato was not killed in the assassination attempt.  His friend Mussa sold his 2% share in InfoCar and betrayed him to the government; he dies, probably by his own hand.  

Vladimir commits suicide.  Mark is assassinated.  

In the end, Plato returns to Moscow, having killed his two biggest enemies, presumably to retake his throne as the titular oligarch.  

Thanks Chuck!