OK, so yes - this is a very slow burn a times with far too many establishing and shots of decaying urban industrialisation, but when the action does actually focus on the story it's not a bad crime drama at all. We start with an arm sticking out of a pile of coal. The cops arrive and "Zhang" (Fan Liao) is soon on the case. He can only identify the corpse, though, and unimpressed his bosses ensure that five years…