By Finger Scans:

The story revolves around four young people. After the death of the president of Sung Han Group, a very prominent group in the world, the heir was to be decided. In the midst of all the commotion, his biological granddaughter was discovered, Jung Hween-Lin, and brought to live in the main house. Though kind and softhearted at first, the money changed her and she became very spoiled and obsessed with her bodyguard, Han Jae-Ha. Han Jae-Ha was initially raised by the president to become the successor of Sung Han Group, but instead now he's become nothing more than a Jung Hween-Lin personal bodyguard and head of the security in Sung Han Group. In order to fully protect her he hires a policeman, Baek Suk-Ho, who despite his old age looks very young and fits in immediately in the high school that they are attending. He joined the police force so he could legally beat up people and doesn't care much about rules or the consequences his actions produce. On one of his missions he meets up with Yoon Lee Sem, a biker gang's leader, who with just a few sentences convinces him to destroy his police cars and makes a breakthrough. Almost causing him to lose his job because of that, he reluctantly accepts the mission to guard Jung Hween-Lin. He then meets up with Yoon Lee Sem once again at high school, who looks completely different from the last time he saw her, which makes him not recognize her at first and befriend her. She, too, becomes Jung Hween-Lin's bodyguard, for unknown reasons, and it seems that Han Jea-Ha and her known each other from before, which adds more to Baek Suk-Ho's suspicion about this whole mission.