The Lumumba Plot: The Secret History of the CIA and a Cold War Assassination by Stuart A. Reid
Democratic Republic of the Congo had a rough start. The region was originally the Belgian King's private realm. It covered an area including many different ethnic groups. White Belgians helped build up the economy with western industrialization. However, the natives were for the most part left out. Only low-level service jobs were open to them. Eventually Belgium was encouraged to turn over power. Alas, things didn't go rail. Many people expected the benefits of the "good life" that the Belgians had without putting forth the effort. There were different people competing for power. Eventually voters selected a prime minister. Alas, things went downhill. The military revolted against their low pay and Belgian leadership. The leader also got caught in cold war machinations and internal conflict. The prime minister and president both relieved each other of their office. The CIA was concerned that the prime minister may be a Soviet tool and plotted his assassination. Eventually he was killed in a plausibly deniable way. A UN plane with the secretary general also crashed around the same time (most likely due to natural causes, but rumoured to have other factors involved.) A new strongman leader was installed and the country stagnated.
The book paints a compelling narrative. However, some of the key names sound similar, make it difficult to keep track of who is who. There is extensive coverage of the UN and the challenge of keeping legitimacy with many competing forces. The CIA plot doesn't come until the end.