I will make it simple & short :-
♡ unpredictable plot which will make u hooked up to this till the end .
♡ yoo seung hoo & Lee Se-young acting skills will blow your mind .
♡ great team work on both side , here I'm taking about the police team of han su mi & baek dong (ML&FL)
♡ you will think this is the villain but end up getting clueless till the end who the real villain is
♡ each episode is unpredictable like u think u guessed it but u know u are clueless , this is what I loved the most in the plot

Ps : I tried to make it short & didn't included any spoilers . I must say this was the masterpiece for yoo seung hoo acting career . No romance , no music still at its best.
" you can always make a right path to bring justice so choose it wisely "