In the not-too distant future, A191, a Codex with artificial intelligence, feels like a misfit in Paradise, a walled city in the middle of an endless desert where humans imprisoned his race long ago. He's not like the others of his kind; he longs to meet humans and make peace with them so man and Codexes can be reunited in the world. These thoughts and feelings are not allowed in Paradise; he risks banishment to the desert by the Overseer A. I. who rules by fear and force. Complicating matters, A191 has a glitch in his programming that conjures up a human boy named Aelius who tells him to go to Old Haven where he will find freedom. However, he's drafted into a rebellion against the Overseer, and as Paradise enforcers close in with orders to terminate him, he escapes the city to wander the desert in search of humans. The journey reveals the truth about his existence, the Overseer's lies, and the consequences of mankind's untethered technology.