In the closing weeks of the war in Europe a security guard on the Manhattan Project is murdered near the Hill. Michael Connolly is sent to Los Alamos from Washington to make sure his death really is the result of a casual homosexual encounter and not connected with espionage. The Nazi regime may be near the end of its reign, but the new enemy of communism has created an atmosphere of paranoia as Oppenheimer and his team come ever closer to concluding the experiment. Connolly is intrigued by the characters on the Hill, by the mixed European background of the victim and by the English wife of one of the scientists. He is caught up in the moral dilemmas which the Project is creating, and discovers that there is a difference between professional and personal beliefs.