A book that describes itself as an "untold story" should generally be met with skepticism, especially when it deals with the Cold War arms race, whose basic story is well known. Yet this thoroughly researched and always interesting book has earned its subtitle: it not only adds intriguing detail to the interplay between Ronald Reagan and Mikhail Gorbachev in the 1980s and gives due recognition to the role of Margaret Thatcher and British intelligence; it also breaks new ground by getting inside the dark and obsessive parts of the Soviet military machine. The "dead hand" of the title was something akin to the Doomsday Machine dreamt up by the nuclear strategist Herman Kahn, in this case a device that would automatically launch missiles against the United States in the event that the Soviet leadership was taken out by a U.S. attack -- a scenario that was actively feared during the fevered early 1980s. As startling a project, because of its lingering effects, was the Soviet Union's work on biological weapons, which resulted in one catastrophic accident with anthrax in Sverdlovsk in 1979 and risked much worse. Hoffman describes the efforts to close down the program just as the Cold War was ending and implies that they never quite succeeded.