The novel’s characters—a mathematician, an exalted violinist, a civil pilot, and a teenage flight attendant—enter the plot burdened by their own problems. Just one night—marked by an aviation incident—ties them into a single knot. And each of them experiences their own “Circle Altitude”—a term in aviation for a layer of airspace in which an airplane is still considered not to have left the airfield. © Viktor Ulin 2007 — photo. © Viktor Ulin 2020 — cover design.