The book tells the story in flashbacks during the actual Mars mission of the chronicalised history until the mission's beginning. The point of divergence for this alternate timeline happens on 22 November 1963, where John F. Kennedy survived the assassination (Jacqueline Kennedy was killed, hence the renaming of the Kennedy Space Center as the Jacqueline B. Kennedy Space Center), but was crippled and thus incapacitated, as Lyndon B. Johnson is still sworn in. On 20 July 1969, Apollo 11 astronauts Neil Armstrong and Joe Muldoon walk on the Moon, and Nixon's "most historic phone call" is joined by a call from former President Kennedy, committing the United States to send a crewed mission to Mars, which Nixon backs as part of his fateful decision to decide the future of crewed spaceflight, instead of deciding on the Space Shuttle program as he did in our timeline.