Evan Galloway is a human limits physiologist working for DARPA--the Defense Advanced Research Projects Administration, the same folks who brought us the internet. Evan's project, of course, is quite different. He's developing a nanotech method for dramatically improving human athletic performance, by increasing the amount of oxygen the human blood can carry. The army wants it for soldiers, but as with much of what DARPA does, there are obvious civilian applications.
Of course, the most obvious of those applications would be classed as cheating. Some people don't mind that, though. Some people are quite comfortable with cheating.
One of those people is billionaire and extreme athlete Jack McKnight--who happens to be the former lover of Evan's boss, Dana Brines. And Dana and Jack have a son together. Or they did, until last year. Michael died suddenly, after running an ultramarathon.