Kim Je-ha (Ji Chang-Wook) was a top special forces soyldier turned mercenary in the Iraq war. He falls in love with a local and is instrumental in getting her a job as an interpreter. His plan to marry his love and get them both out of the war theater goes terribly awry when she witnesses something she shouldn't and is killed in front of Je-ha's eyes. Worse he is framed for her murder. He is determined to seek revenge and escapes, for a time to Barcelona where he runs across a beautiful young woman who seems to be running from someone and pleads for his help. The girl is Go A-na (Im Yoon-ah) who has been kept as a veritable prisoner her whole life to protect her father's political aspirations.

Unsure if the young woman is crazy or indeed in danger Je-ha only half heartedly helps her and she is re-captured by her step mother's guards. As the result of an illegitimate relationship, Go A-na is kept under tight guard.

Fast forward back to South Korea and a series of events results in Je-ha, who is in hiding in his home country, catching the attention of Presidential candidate's wife, Choi Yoo-Jin (Song Yoon-ah) Realizing his skill as a great asset to her security team, she offers to provide an alias for him and ultimately an avenue to clear his name. Je-ha is assigned the code name K2 and is surprised to discover his first assignment is to guard the girl he ran across in Barcelona. Yoo-Jin and Je-ha find they have a common enemy, Park Kwan-soo (Kim Kap-so) who is political rival to one and fiancé murderer of the other. Meanwhile Jang Se-Joon (Jo Sung-ha) has allowed his wife to imprison A-na with the promise to not cause her physical harm.
While guarding her, K2 gets to know A-na and understands that past tragedy has led to her current fragile psychological state which is not completely unlike his own. The two find love but must navigate the danger of a political world full of lies, murder and corruption. Some will stop at nothing to gain the ultimate seat of power. A-na is not the only one who finds K2 attractive A-na's stepmom has been in a loveless marriage as a rich heiress able to fund her husband's political ambitions but having lost his heart to A-na's mother. She has possibly done the unthinkable once to remove a romantic rival and A-na is already a constant reminder of her husband's infidelity so Yoo-jin needs no excuse to eliminate her. K2 must play a dangerous game to free and protect the woman he loves while maintaining the alliance he needs to exact his revenge.
This has everything I love in a good action movie. It was sort of James Bond meets Bruce Lee. I was not sure Ji Chang-Wook could play another character I liked as well as Healer but I have to say he did. He plays this almost super hero level character with a vulnerable streak that has you rooting for him the whole way. The A-na character led such a sad life that it was a happy moment when K 2 entered the picture as you knew he would make things right. The plot was complex and every other character was such a twisted blend of good and evil it kept you guessing to the end. I loved this movie and thoroughly enjoyed it. Chemistry between the leads was perfect and believable. It had a nice romantic element. The only slight flaw was the overly obvious product placement it broke the fourth wall several times. Highly recommend yet another excellent Ji Chang-Wook action movie.