My best friend would never forgive me if I didn't take this opportunity to urge you in the strongest possible terms to watch Stranger (Secret Forest) with Bae Doona and Cho Seungwoo. I also agree: a tale of rampant police corruption and Bae Doona doing the absolute most. There are lots of wonderful relationships, foremost the one between Bae and Cho, which is not romantic, but profoundly touching. It's a dark -- it's a murder mystery -- but it's not over-the-top, and it definitely wraps up the mystery well.