The book covers several periods from the life of Lazarus Long (birth name: Woodrow Wilson Smith), an early beneficiary of a breeding experiment designed to increase mankind's natural lifespan, known as the Howard Families, after the program's initiator. More of a result of a mutation then the breeding experiment, he is the oldest living human, now more than two thousand years old.
The first half of the book takes the form of several novellas connected by Lazarus's retrospective narrative. In the framing story, Lazarus has decided that life is no longer worth living, but (in what is described as a reverse Arabian Nights scenario) agrees not to end his life for as long as his companion, chief executive of the Howard families, and descendant Ira Weatherall, will listen to his stories.
"The Tale of the Man Who Was Too Lazy to Fail"
This story concerns a 20th-century United States Navy cadet named David Lamb who rises in the ranks while avoiding any semblance of real work or combat by applying himself enthusiastically to the principle of "constructive laziness". Shortly after telling the story Lazarus mistakenly calls David "Donald", which is intended to make the reader think the story is fallacious, while actually pertaining to Lazarus directly.
"The Tale of the Twins Who Weren't"
Lazarus tells of his visit as an interplanetary cargo trader to a planet, where he bought a pair of slaves, brother and sister, and immediately manumitted them. Because they had no knowledge of independent living, nor any education, Lazarus teaches them "how to be human" during the voyage.
The two were the result of an experiment in genetic recombination in which two parent cells were separated into complementary haploid gametes, and recombined into two embryos. The resulting zygotes were implanted in a woman and gestated by her, with the result that although both have the same surrogate mother and genetic parents, they are no more closely related genetically than any two people taken at random. They have been prevented from sexual relations by a chastity belt; but having confirmed that there is no risk of genetic disease in their offspring (described as the only valid reason against incest), Lazarus solemnizes their marriage and later establishes them as the owners and operators of a thriving business. At the end of the story, he reveals that the twins looked the same age decades later, and expresses his belief that they were his own descendants, from an earlier period when he had been a slave on the same planet.
"The Tale of the Adopted Daughter"
A short scene-setter introduces a planet where Lazarus has led a group of pioneering colonists.
Lazarus, now working as a banker and shopkeeper and keeping his true age secret, saves a young girl named Dora from a burning building and becomes her guardian. When she grows up, he marries her, and the two become founders of a new settlement where Lazarus' long life is less likely to be noticed. They are successful and eventually build a thriving community. Because Dora is not a descendant of the Howard Families, the source of their longevity, she eventually dies of old age, leaving Lazarus to mourn.
At the beginning of this story, Lazarus has regained his enthusiasm for life, and the remainder of the book is told in a conventional linear manner. Accompanied by some of his descendants, Lazarus has now moved to a new planet and established a polyamorous family consisting of three men, three women, and a larger number of children, two of whom are female clones of Lazarus.
In the concluding tale, Lazarus attempts to travel backward in time to 1919 in order to experience it as an adult, but an error in calculation places Lazarus in 1916 on the eve of America's involvement in World War I. An unintentional result is that Lazarus falls in love with his own mother. To retain her esteem and that of his grandfather, Lazarus enlists in the army. Eventually Lazarus and his mother, Maureen, consummate their mutual attraction before Lazarus leaves for the war.[nb 1]
In the trenches of the Western Front in France, he is mortally wounded, but rescued at the last moment by his future companions from the framing story and returned to his own time.
The Notebooks of Lazarus Long
There are also two "Intermission" sections, each some six or eight pages long, taking the form of lists of provocative phrases and aphorisms not obviously related to the main narrative. These were later published independently, with illustrations, as The Notebooks of Lazarus Long.