The science is settled. The road is rationed. Thousands of lives are waiting on the wrong side.
Nora Vale proved that concentrated corridor use is killing the sky. Earth answered by putting the Sable throat under guns.
Priority now belongs to defence, licensed freight and the systems judged essential to civilisation. Refugee hulls carrying the last scattered families of dying worlds wait behind them. Captain Aidan Locke's command survives at the pleasure of the authority holding the corridor. Jae Wells watches honest procedure become a machine for deciding whose lives can be postponed. Ravi Sethi keeps the names of people policy has reduced to cargo.
When a Ferren transit is turned away and the reach-side coalition moves to stand beside it, the Cairn becomes the centre of a confrontation no side can retreat from cleanly.
Every lawful choice preserves the system. Every human choice risks breaking it. And the only route that may save the convoy carries the same cost Vale warned them about from the beginning.
The Dawnward was built to open roads. Now her crew must decide whether a road can still be worth opening when they finally understand what it takes from the sky.
The Closing Sky completes the Wide Sky Trilogy: a character-driven hard-SF finale about command, evidence, refugee survival and the moment a bright civilisation discovers abundance was never free.