The Cat Who Walks Through Walls
Robert A. Heinlein
 A writer seated at the best restaurant of the space habitat "Golden Rule" is approached by a man who urges him that "Tolliver must die" and is himself shot before the writer's eyes. The writer–Colonel Colin Campbell, living under a number of aliases including his pen name "Richard Ames"–is joined by a beautiful and sophisticated lady, Gwendolyn Novak, who helps him flee to Luna with a bonsai maple and a would-be murderer ("Bill"). After escaping to the moon, Gwen refers to the now ancient Lunar Revolt (as described in The Moon Is a Harsh Mistress) and Mike (Mycroft), the self-aware computer responsible for the uprising's victory, and claims to have been present during the revolt; despite her claim that she was only a girl at the time, Campbell grows suspicious, and learns that she is a rejuvenation of the revolution's most prominent female leader. Still pursued by assassins, Campbell and Novak are rescued by an organization known as the Time Corps under the leadership of Lazarus Long. After giving Campbell a new leg to replace one lost in combat years before, the Time Corps attempt to recruit Campbell for a special mission. Accepting only on Gwen's account, Campbell agrees to assist a team to retrieve the decommissioned Mike. Engaged in frequent time-travel, the Time Corps has been responsible for changing various events in the past, creating an alternate universe with every time-line they disrupt. Mike's assistance is needed in order to accurately predict the conditions and following events in each of the new universes created. Campbell's frequent would-be assassins are revealed to be members of contemporary agencies also engaged in time manipulation who, for unknown reasons, do not want to see Mike rescued by the Time Corps. During the mission, Gwen is grievously wounded and Campbell loses his foot again, though the Time Corps succeed in retrieving Mike. The story ends with Campbell talking into a recorder (presumably the source of the first-person medium through which the story is told) reflecting on the mission and his relationship with Gwen.