The list of VERY GOOD British police crime thriller series that I have seen is really long, unfortunately I will not add this one to that list.
Leila Farzad has the right appearance to portray Lou. She does a good acting job, one moment she is unapproachable and self-confident, but later maybe the viewer also sees the doubt and moral conflict shine through. I didn't saw and felt that at all, for me she is simply a terrible woman, selfish as hell. Let's be honest, come on!, will she continue to be corrupt or make a new beginning after an incident involving a loved one? There's no way you'd dance with the devil if you had a family to protect.
By the way, I loved all the actors.
In general I enjoy the series, but it also left me a little dissatisfied, and I would have loved a more realistic and rougher ending, something more creative and raw, simply what they deserve. Behind the plot I think there is a psychological study, can people change? In this specific case I would say NO.
To finish, I recommend you see it. The dialogues and tension are palpable, I must admit that at times it left me on the edge of the couch. Despite its many flaws.