Stoyte hires Dr. Obispo and his assistant Pete to research the secrets to long life in carp, crocodiles, and parrots.

Jeremy Pordage, an English archivist and literature expert, is brought in to archive a collection of rare books.

For this reason, he sees any effort to extend human lifespans—the very work that Stoyte had hired Dr. Obispo and Pete to do, as nothing but "a couple of extra lifetimes of potential evil.

One evening, Obispo visits Jeremy, who reads to him from the diaries of the Fifth Earl of Gonister, written in the late eighteenth century.

He accidentally kills Pete (whose thoughts and morals had slowly started to expand under Propter's tutelage) instead.

This takes him, along with Virginia and Stoyte, to Europe, where they find the Fifth Earl, now 201 years old[4] and living locked in a dungeon with a female housekeeper, whom he beats.

[6] These characters expose questions and answers depicting their various life philosophies until the climax in a Socratic method, while explorations of mortality, eroticism, class struggle, mysticism, and greed are all presented dispassionately throughout.

The evolutionary principle of neoteny (a phenomenon of adult retention of juvenile-like morphology or behaviour) has been invoked to explain the origin of human characteristics from ape ancestors.

The storyline suggests that if we lived longer, we would continue to develop along the path of an ape and eventually become ape-like.

The story has been interpreted [citation needed] as the British Huxley's contemptuous nod to the Hearstian reality of the United States in the early part of the 20th century: Jo Stoyte is an allegory for William Randolph Hearst by his acquisitions of art, etc., and living in an opulent estate—similar to Hearst Castle—with Virginia, who can be taken as a parody of Marion Davies.