A bizarre novel with a many-worlds background. An organization claims to be sending its agents to temporarily take over bodies in different versions of our world, to fix things by simple means like delaying a good person on the way to catch a plane that will crash, to assassinating bad people.

But some agents become doubtful as to whether the organization itself is becoming corrupt.

Different from his Culture novels in most ways but still using an alternate reality (or many alternate realities) to explore some social and philosophical issues.