The truth was quieter and harsher than either cynicism or idealism: peace, in Lyra, was an ongoing act of design and moral accounting, an experiment in which the city tried — imperfectly and with evidence at hand — to keep harm small and hope alive. They called it Lyra — a city whose name came from a constellation kids traced on the ceiling of school auditoriums when the power went out. From a distance it looked like all the other carefully ordered cities: low-rise apartments with balconies overflowing with laundry, tramlines humming at regular intervals, a park with a pond that mirrored the sky. Up close, the streets had been engineered for calm: sightlines kept short and pleasant, benches faced one another so strangers became acquaintances, lamp posts lit places where shadow once hid. Even the graffiti had been curated into murals that made people smile. For a long while Lyra kept a kind of fragile miracle: no homicides, few assaul...