Intriguing speculation on a major historical turning point, from the veteran editor-writer (Mars, p. 503, etc.)--namely, what if Franklin Delano Roosevelt had lived and Josef Stalin had died? Well, in Bova's persuasive April 1945 scenario, FDR, having quit smoking, consequently never dies of a stroke. Elsewhere, that master of intrigue, Winston Churchill, plots Stalin's assassination: hidden inside the Sword of Peace presented to the dictator at Yalta was a wafer of deadly plutonium; ambitious Soviet security chief Beria arranges for the plutonium to be placed inconspicuously in Stalin's desk--and within weeks the dictator is dead of a "mysterious" illness. A Kremlin power struggle ensues, crucially delaying the Soviet assault on Berlin. In the Western Allies camp, meanwhile, after much arm-twisting by Churchill, FDR orders General Patton's Third Army to advance on Berlin; in clue course, the city falls to a combined American and Soviet assault. Patton, however, fails to survive his triumph when his jeep hits a land mine. And the long-term consequences of all this, barely hinted at in the narrative: no postwar Soviet domination of Eastern Europe, no cold war, and no nuclear-arms race. Though sometimes blurred in the fine detail (Bova has problems with British speech and idioms, for instance): a low-key, convincing what-if, stuffed with famous figures and likely to tempt WW II buffs, as well as Bova fans and sf regulars.