It's hard keeping one story plot running over six episodes, very few series do it successfully. This one didn't do it for me, it wanders and meanders and a red herring here and a red herring there, but an inexperienced journalist who is diverted by an affair didn't focus it. I prefer police procedurals because they are focused and you get facts and evidence piece by piece and you get a conclusion. This series started moving by episode 4, but I gave up.
This is another typical family who has suffered a great loss and parents who can't move on. Nothing new, we've watched it before. Joanna Scanlan, Iwan Rheon and most of the cast are good, but
good acting doesn't make up for a bad script. I wanted to like it, but it would have been better as a 3 episode series and not 6. It's a depressing series to watch.
The Pembrokeshire Murders series was a true story in Wales and it was fast and focused and kept my attention. There is a lesson there, but sadly I doubt producers and writers will take it.