The world is managed by a central computer called UniComp (referred as just "Uni" in speech), which has been programmed to keep every single human on the surface of the Earth in check.

People living under the "Unification" are continually drugged by means of monthly treatments (delivered via transdermal spray or jet injector) so that they will remain satisfied and co-operative "Family members."

Everyone is assigned a counselor, who acts somewhat like a mentor, confessor, and parole agent; violations against "brothers" and "sisters" by themselves and others are expected to be reported at a weekly confession.

In part, people who choose by evasion and modifying their own behavior to leave the main Family are subtly redirected to "nature preserves" of imperfect life on islands.

Despite the name, the "programmers" are not allowed to program Uni since Wei Li Chun, the person who started the Unification, reserves the privilege solely to himself.

Even the basic facts of nature are subject to the programmers' will: men do not grow facial hair, and it rains only at night.

There are only four personal names for men (Bob, Jesus, Karl, and Li) and four for women (Anna, Mary, Peace, and Yin).

Through his grandfather's encouragement, he learns how to play a game of "wanting things," including imagining what career he might pick if he had the choice.

As Chip grows up and begins his career, he is mostly a good citizen but commits minor subversive acts, such as procuring art materials for another "nonconformist" member who was denied them.

There, they learn that UniComp, as a last resort, has planted failsafes that eventually lead all incurables to the islands, where they will be trapped forever from the treated population.

For example, to deceive Wei, Chip consents to the replacement of his green eye with a brown one even though it involves giving up a cherished part of his identity.

However, nine months later, a new group of incurables arrives, and Chip leaves the welcome party with the intention of using the newcomers' explosives to blow up the master computer.

The book ends with Chip riding a helicopter toward Majorca, where Lilac, their son, financial sponsors, and friends are hopefully waiting for him.

For the first time in his life, he sees raindrops in daytime, nature's affirmation that the era of slavery and total control is finally over.

Cherry Wilder, discussing This Perfect Day, stated, "The ideology of the "utopia" is weak, but the quality of the writing and the level of invention are high.

"[2] David Pringle gave This Perfect Day two stars out of four and described the book as "a slickly-written update of Aldous Huxley's Brave New World, lacking in originality but very professionally put together.