The Mary Sue element jumps out at you, it's so loosely written that you could get three better books if all the tropes were followed, and there are contradictions throughout the book. The reason we were reading this one, instead of a newer non-related book (Survivor), is because DAW put out a 10th anniversary edition and the library was able to get them cheaper.
Essentially, there's a paranormal group of beings who can move and talk and so forth through an immaterial substance. They have developed their power to a point where they no longer have enough diversity to continue to have kids. They think up an idea that might work and send one of them off with her mind blank. She interacts with humans and other aliens and eventually, we and she find out what happened.
It's really a romance/soap opera and I didn't like having to reread it.