I agree that the Mao story arc is not very clear (yet) in the TV show. I didn’t read the first book, (but did read the second and third books) so I don’t really know if that’s the way it is meant to be at this stage. I think perhaps it’s not meant to be clear yet.
Anyway (some minor spoilers):
[spoiler] Idealist, Julie Mao, ran away from home to train with and join the OPA on Ceres. Her extremely wealthy father, owner of Mao-Kwikowski Mercantile, just happened to own shares in the security company on Ceres that employs Miller, so her father ordered that company to search for her and kidnapp her back home. Miller was the investigator chosen to do this. But Julie was already on an OPA mission which is about to go horribly wrong … and I won’t say anything more about that.
So, because Julies father is also involved in the research company Protogen that is somehow also mixed up in Julie’s OPA mission, he knows Julie is “gone” and calls off the search for her. Miller, who is becoming obsessed with the search for Julie, is dismissed, because he won’t let it go. He hasn’t found out much yet, I think, other than that Julie was somehow connected to the OPA.
The wierd scene involving the pilot was, I think, just a set-up to get us ready for a key scene late on where something universe changing is first discovered (I’m not telling you what!). Anyway, these thrillseeker pilot/jockeys are just trying to slingshot themselves around planets? and back home at ridiculous speeds to show off to each other. More often than not, something goes wrong with their build or their calculations are off and they esplode.[/spoiler]