Leap Ships — Michelle L. Levigne

Commonwealth history says part of the reason for the Downfall was because some people were classed as mutants and made into slaves, and the slaves eventually rebelled. Bain and Lin go on an exploring mission and meet Leapers - descendants of people who escaped from the abuse and slavery of First Civ. Leap ships travel vast distances in a few heartbeats by slipping through the fabric of space and time. Journeys of years with Spacer pilots take days on Leap ships. Captain Lorian and the crew of the Estal'es'cai have come to see if anything remains of their galaxy and the civilization where their ancestors originated. What Lin and Bain do on meeting the Leapers could affect the future of the Commonwealth. Then, while exploring a desert world that could be the birthplace of the Leaper race, they run into an old friend. Or is he an old enemy?