This one is trashy. The story is wildly unbelievable, with paper-thin motivation and plotting for the characters, especially the murderer.
Anthony Flanagan is pretty dull in this. He plays the supposedly high-flying but uptight DCI in charge of the case. He is more or less a charisma-free automaton for large parts of the story, but gets to emote a bit near the end. Actually the character is boring. How he's supposed to have become a DCI by his early thirties is the biggest mystery in the programme.
Tom Ward is not good here either. He is cut out to play nice guys who are possibly slightly impulsive (his role in Silent Witness), and that's basically what he does here. Unfortunately he can't decide about his accent (he sporadically tries to sound northern). The supposed actions of his character are laughable and not sufficiently explained or supported by what has gone before.
We're living in times like those of the Roman Empire. Sensationalism for the masses is the order of the day. In this type of film the murders seemingly have to get more and more horrid with more and more shots of putrefying bodies and the like. Why do film makers have to be such slaves of fashion and the Zeitgeist?