In the One State of the Great Benefactor, there are no individuals, only numbers. Life is an ongoing process of mathematical precision, a perfectly balanced equation. Primitive passions and instincts have been subdued. Even nature has been defeated, banished behind the Green Wall. But one frontier remains: outer space. Now with the creation of the spaceship Integral, that frontier--and whatever alien species are to be found there--will be subjugated to the beneficent yoke of reason.

One number, D-503, chief architect of the Integral, decides to record his thoughts in the final days before the launch for the benefit of less advanced societies. But a chance meeting with the beautiful I-330 results in an unexpected discovery that threatens everything D-503 believes about himself and the One State. The discovery--or rediscovery--of inner space...and that disease the ancients called the soul.