On the peanut-shaped planetoid of Ut, a 150-million-year-old computer named Mamacita rules with dictatorial control. Her every whim is a steadfast rule, and no command is stronger than the ban of Sudanna, the wind that sweeps across Ut spreading the liberating sounds of music.

Hiley OIV is one of Ut's most conscientious inhabitants, a man so afraid of losing his head (utpeople have very precarious necks) that a Bad Thought almost never enters his mind. But now his teenage daughter has fallen in love with Prussirian BBD—Ut's most notorious outlaw—a man who has broken Mamacita's cardinal rule: he makes music.