The implosion of the Soviet Union was the culmination of a gripping game played out between two men who intensely disliked each other and had different concepts for the future. Mikhail Gorbachev, a sophisticated and urbane reformer, sought to modernize and preserve the USSR; Boris Yeltsin, a coarse and a hard drinking “bulldozer,” wished to destroy the union and create a capitalist Russia. The defeat of the August 1991 coup attempt, carried out by hardline communists, shook Gorbachev’s authority and was a triumph for Yeltsin. But it took four months of intrigue and double-dealing before the Soviet Union collapsed and the day arrived when Yeltsin could hustle Gorbachev out of the Kremlin, and move in as ruler of Russia. Conor O’Clery has written a unique and truly suspenseful...