Révi and the City of Dreams

Welcome to the City of Dreams. A perfect place governed by the all-knowing artificial intelligence, Omnicloud. Everyone here lives in safety, plenty, and good health. Well, almost everyone.

Fifteen-year-old Révi has suffered from an incurable illness since birth, which has one very strange side effect. Unlike the other inhabitants of the City, he has not lost the ability to dream at night.
When he begins to have remarkably vivid dreams in which a mysterious dark-haired girl begs him for help for the forgotten world beyond the city Wall, Révi initially doesn't take it seriously.
Shortly after, however, information comes from Omnicloud that is completely the opposite: The Wall is crumbling and the City of Dreams is threatened by an attack from the people of the Wilderness. But where does the truth lie?

Can a person trust their dreams? Or should they rely on a perfectly functioning system that has never failed before?