Dave Dryden and his pal Shel have a great life traveling through time, visiting with Napoléon and da Vinci, until Shel dies. Or does he?

I was lucky enough to meet Jack McDevitt at Jim Gunn’s workshop in Lawrence. He was always encouraging, kind, insightful and upbeat—for me, the best of the resident writers at the workshop.

Early in the novelization of the story, Shel has a conversation with his dad about the chronological integrity principle. There is only one timestream, and if we try to do anything to change what is already known about the stream, then time will stop us. On the other hand, if we can arrange for an event to happen that meets the known facts without being quite what we thought it was. . .