Leap Ships (Commonwealth Universe: Age 3, #8)

Vidan was again reaching out to the stars: sadder and wiser...and cautious, unwilling to repeat the mistakes of the ancestors. The Commonwealth was born, reaching out to lost colonies and establishing new ones, rediscovering lost technology and how to navigate the star-ways. Many of the lost colonies not only survived but thrived--and they remembered their abandonment and the harsh centuries of the Downfall...

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 and escaped.

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.

While exploring a desert world that could be the birthplace of the Leaper race, they run into an old friend. Or is he actually an old enemy?