I love this korean drama so much!! I just finished watching it! It is an action-packed series with korean politics involved (just fictitious but could be applicable), heroism, good vs. bad, searching for identity and romance is also included. A lot of twists and turns and I felt so many mixed emotions (happy, sad, nervous, afraid, betrayed, loss, anger, frustration, wonder and more). It was really amazing and most of the time the ending of each episode is open-ended so I felt like wanting to watch the next episode at once! :)
You can watch here: http://www.youtube.com/watch?v=NTdHy6FqxSk