First of all there are no 4 knights because I don't care what other people say but the secretary doe not count. It's been a while since I've watch the show so I don't remember the details just that I hate the show. I think that there are many other dramas thats are so much better. the casting was good so was the acting but the story line... I just did not like at all.
I would say skip the drama you'll save your time and would be doing yourself a favour:) I just feel a drama should have a male and female lead and at the most one love interest. I personally don't like shows where there are multiple love interests especially when the love interests and the male lead are close like friend/brothers. For example Boys Over Flowers. I know many people love love that show but not me. I believe its better when the FL is close to the ML friends thats it no more. As it shows a stronger bond and better character Development.