Caution: there are vague but minor spoilers her if you have not seen it. My wife and I have so much British television lined up to watch that we can be a tough audience sometimes. But as this series started out, it held our attention just fine. The core family of sisters held my interest and I cared about what happened to them. You can't ask for more than that. I rank the first three episodes fairly highly. My interest in the story started to slip during the fourth and fifth installments, and I wasn't even sure why as I watched it. Now I think that part of it was that I couldn't understand…