Paul McAuley - Cowboy Angels

The first Turing gate, a mere hundred nanometers across, is forced open in 1963, at the high-energy physics laboratory in Brookhaven; three years later, the first man to travel to an alternate history takes his momentous step, and an empire is born.For fifteen years, the version of America that calls itself the Real has used its Turing gate technology to infiltrate a wide variety of alternate Americas, rebuilding those wrecked by nuclear war, fomenting revolutions and waging war to free others from communist or fascist rule, and establishing a Pan-American Alliance. Then a nation exhausted by endless strife elects Jimmy Carter on a reconstruction and reconciliation ticket, the CIAs covert operations are wound down, and the Real begins to wage peace rather than war.But some people believe that it is the Reals manifest destiny to impose its idea of truth, justice, and the American way in every known alternate history, and theyre prepared to do anything to reverse Carters peacenik doctrine. When Adam Stone, a former CIA field officer, one of the Cowboy Angels who worked covertly in other histories, volunteers for reactivation after an old friend begins a killing spree across alternate histories, his mission uncovers a startling secret about the operation of the Turing gates and leads him into the heart of an audicious conspiracy to change the history of every America in the multiverse--including our own.Cowboy Angels is a vivid, helter-skelter thriller in which one version of America discovers the true cost of empire building, and one man discovers that an individual really can make a difference.