Marooned in Realtime is a 1986 murder mystery and time-travel science fiction novel by American writer Vernor Vinge, about a small, time-displaced group of people who may be the only survivors of a technological singularity or alien invasion.

The "high-techs" — those who had the advantage of ever accelerating progress — have vastly superior technology, including cybernetic enhancements, faster and thought-controlled bobblers, personal automaton extensions of self, space ships, medical technology to allow practical immortality (barring accidents or fatal injuries), and individual arsenals greater than those of entire 20th century countries.

Some time after the events in The Ungoverned, Brierson was unwillingly bobbled 10,000 years into the future while he was investigating a routine theft, cutting him off forever from his wife and children.

Yelén and Marta Korolev, a high-tech couple, have spent 50 "megayears" (million years) gathering together all the survivors they can find to rebuild civilization, with the ultimate goal of creating their own technological singularity.

When the "murder" is discovered, Yelén Korolev recruits the low-tech Brierson, the only person with expertise in crime-solving, to find the killer.

Through skillful maneuvering (and a good deal of luck), Brierson manages to seize the monster's own hidden zygote bank and birthing equipment when the latter is forced to flee for his life, making it possible to restore the human race.