The stars are going out.
But they aren’t truly stars.
They are cities for a long forgotten race of people, the Starlings. These Starlings have protected the humans down below from other peoples who would wish them harm, but now they face an enemy they have no hope of defeating. In order to warn the humans of the war that is to come, they send down an ambassador. But the humans have problems of their own they must face before they can deal with the war the Starlings are losing.