Kim Soo-Hyun is an elite assassin. He kills his targets and disappears. His identity like race, age or name is unknown to others. Individuals, gangs and organizations from all over the world hire Kim Soo-Hyun. Deep within his mind, he wants to have affection from people. Now, Kim Soo-Hyun has to kill to find his family. Do Hyun-Jin graduated at the top of her class from a police university. She is an excellent detective who is also arrogant. She is usually dressed fashionably. Do Hyun-Jin comes across as cold-hearted, but she sympathizes with those in painful situations. Now, Do Hyun-Jin chases after Kim Soo-Hyun to reveal a mystery related to her lover's death.