The Moscow Option by David Downing

This provocative alternative history looks at WWII from a new angle-what might have happened had the Germans taken Moscow in 1941.
Based on authentic history and real possibilities, this unique speculative narrative plays out the dramatic and grotesque consequences of a Third Reich triumphant. In this terrifyingly plausible scenario, the Germans fight their way into the ruins of Moscow on September 30th, 1941-and the Soviet Union collapses.
Although Russian resistance continues, German ambition multiplies after this signal success. They launch offensives in Africa, the Mediterranean, and the Middle East. Hitler's armies, assured of victory, make their leader's dreams reality and Allied hopes of recovery seem almost hopelessly doomed.
With a convincingly blend of actual history and alternate events, The Moscow Option is a chilling reminder that history might easily have been very different.