I did read through some of the 24 plot summaries, but couldn't figure out the Audrey/Jack connection. Thanks to all for your posts. Now I get it...
Jack is sort of like a reluctant Dirty Harry character in that he gets all the sh1t jobs with little thanks from anyone else. They have introduced personal elements to his life that Harry Callahan never had to deal with and he gets his ass kicked far more than Dirty Harry ever had to.
One of the themes of the show is that we need people like Jack doing the job he does but many people cannot stomach the process. Audrey was a weakling. She quit on her marriage rather than be the woman that she needed to be in order to have it work out. Then, when Jack saves her and her father's bacon and her ex stands in the way of Jack doing what he needs to she turns on him. Jack is always about sacrifice and putting the bigger picture in front of everything else. Audrey couldn't deal with that.
Best bet - buy or rent the previous seasons. I have watched previous on DVD. This is the first seasin I gave watched on TV.