So now story is kinda predictable. He is telling story by that comic novel. His family is related with the bad people. He like the girl but can't be with her because he thinks he is guilty and that why trying to solve that case on his own. I guess then should start dating by the end of episode 4 or 5 and we might see a breakup for 1-2 episodes around 12-13 episodes.
So its about ex lover meeting again. K drama should try something in romance. Childhood friends, ex lovers meeting again there are already a lot of dramas with this trope.