Cowboy Angels (Gollancz)

"The first Turing gate, no bigger than a fleck of dust, is forced open in 1963, at the high-energy physics laboratory in Brookhaven; three years later, the first man to enter an alternate history is sent through a much larger version, and an empire is born." "For fifteen years, the version of America that calls itself the Real has used Turing gates to infiltrate a wide variety of alternate Americas, rebuilding those wrecked by nuclear war, and fomenting revolutions to free others from Communist or Fascist rule, establishing a Pan-American Alliance. Then a nation exhausted by endless strife elects Jimmy Carter on a reconstruction and reconciliation ticket, and the Real begins to wage peace instead of war." "But some people believe that it is the Real's manifest destiny to impose its idea of truth, justice and the American way in every known alternate history, and they're prepared to do anything to reverse Carter's peacenik doctrine. Adam Stone, one of the CIG's covert field agents, or Cowboy Angels, 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 audacious conspiracy to change the history of every America in the multiverse - including our own."--BOOK JACKET.