I enjoy this drama immensely. Not only for the obvious reason of watching Jang Hyuk but also because of the two female detectives who are more competent, less submissive, helpless and docile than females are usually portrayed in Kdrama world.
Watching Jang Hyuk - who is known as an action man - playing a character who is physically incapacitated in more than one way and forced to sit still and immobile in a wheelchair for the first couple of episodes is a revelation!

The early scenes with profiler Oh Hyun Jae in his hideout instructing the young female rookie detective were amazing and demonstrated what a brilliant actor Jang Hyuk is - because I was never not completely mesmerised by his performance and wanting to find out what Oh Hyun Jae was going to do or plan next.
The actor must have relished this chance to play against type as it is very much the complete opposite of what he is usually asked to play (at least in the first few episodes...)