[1] Most but not all of the edits made for the serialized version were restored for the first paperback publication by Ace Books and the title was changed by the publisher to This Immortal.
Conrad Nomikos, the first person narrator, is a man with a past which he would rather not talk about who has been given a task which he would rather refuse: to show an influential Vegan named Cort Myshtigo around the old ruins of Earth.
The group has a run-in with a cannibal tribe, a close encounter with several mutated and dangerous lifeforms, and Myshtigo is horrified to learn that Conrad is having the pyramids of Egypt torn down to provide building material for new constructions.
In the final battle to protect the Vegan, Cassandra, having escaped the cataclysm at sea in Conrad's yacht, appears and delivers the decisive saving blow.
Myshtigo sees the mettle of which Conrad is made, and decides to leave the planet in the possession of the one being with the longevity, power and moral fiber to do well by it.
Identified early in the book as a possible "Kallikantzaros"[3] by his lover Cassandra (who exhibits the same abilities as her namesake to foretell the future but not be believed), Conrad is later also compared to Pan.
Whether or not Conrad is a god, however, is left unclear in the book: while he has led an extraordinarily long life, it is hinted that this could be the result of mutation due to the nuclear war.
"[4] Algis Budrys praised This Immortal as "an extremely interesting and undeniably important book", describing it as "a story of adventures and perils, high intrigue, esthetics [and] politics ... utterly charming [and] optimistic".