[1] A passionate animal lover and skilled veterinarian, no one would suspect that Kim Soo-hyun (Jang Ki-yong) is actually one of the most lethal men in the world.

On the opposite extreme, is Do Hyun-jin (Nana), a tenacious detective whose external cold image hides an empathic soul.

Using an effective combination of skill and instinct, Do Hyun-jin ends up working on a case that leads her directly to Kim Soo-hyun.

Believing that he is the serial killer she seeks, Do Hyun-jin thoroughly investigates the identity and past of Kim Soo-hyun, but what she finds shakes her to the bone.

One day, Pavel decides to complete one last job before officially handling the helm to Soo-hyun but his illness prevented him in killing his target, a mafia boss.