Alekhines Gun - Book 1 of The Recollection Paradigm

The continent of Amon remains as the last bastion for the various mortal races, the rest of the planet extinguished by the mysterious Unthinkable a century past. The scattered Colonies function mostly in isolation, and travel between them is treacherous indeed. But a pair of Skytouched sisters make a living in the hazardous Wastes, their skill in combat seeing many a traveler safely to their destination. When a man named Alekhine approaches them, he seems like just another ordinary customer...