The Incrementalists — Steven Brust; Skyler White

The Incrementalists -- a secret society of two hundred people with an unbroken lineage reaching back forty thousand years. They cheat death, share lives and memories, and communicate with one another across nations, races, and time. They have an epic history, an almost magical memory, and a very modest mission: to make the world better, just a little bit at a time. Their ongoing argument about how to do this is older than most of their individual memories.

Phil, whose personality has stayed stable through more incarnations than anyone else's, has loved Celeste -- and argued with her -- for most of the last four hundred years. But now Celeste, recently dead, embittered, and very unstable, has changed the rules -- not incrementally, and not for the better.

Now the heart of the group must gather in Las Vegas to save the Incrementalists, and maybe the world.