Life is now totally fulfilled and sustained within Urban Monads (Urbmons), mammoth thousand-floor skyscrapers arranged in "constellations", where the shadow of one building does not fall upon another.

Each building can hold approximately 800,000 people, with excess population totalling three billion a year transferred to new Urbmons, which are continually under construction.

The Urbmons are a world of total sexual license where men are expected to engage in "nightwalking"; it is considered very rude to refuse an invitation for sex.

Although great effort is spent to maintain a stable society, the Urban Monad lifestyle causes mental illness in a small percentage of people, and this fate befalls two of the book's main characters.

There are usually no trials, and punishment is swift; anyone who threatens the stability of the Urbmon society (a "flippo") is "erased" by being thrown into a shaft that terminates in the building's power generator.