It's a programme that can't see a fine line without walking towards it and treading catlike along it until it vanishes over the horizon. It moves from light to dark between scenes and within scenes. Benton is a naïf, a compulsive truth-teller living within an absurdly strict moral code and pathologically polite and literal mindset without ever being idiotic or unconvincing. He has impossible skills (tracking people through the mean city streets as he used to track caribou through the northwest territories as a boy) in a determinedly realistic setting. Ray is a hardbitten, cynical motormouth with an idealistic soul struggling wearily to shine through.
This article goes a long way to capturing what I loved about that series.