Han Tae-sung (Song Seung-heon), a former gang member and current businessman, has a life full of mystery and twists and turns. The first time he felt the feeling of love in his life was during his time in the underworld. Seven years ago, Han Tae-sung was asked by the gang to go to a bookstore to collect debts. The owner of the bookstore, Xu Jingxu, owed a gangster loan shark. Knowing that her father owed a huge debt, his daughter Xu Meidao (Shin Se-kyung) decided to dedicate herself to Han Tae-sung for the sake of her family. In Meidao, Taicheng saw the shadow of his childhood. So he quietly funded the tuition for Meidao and his younger brother Meijun, hoping that Meidao would not go astray like him. But one day, Meidao was captured by the underworld, and Taicheng struggled to save him. At the cost of a scar on his back, Taicheng regained his memory, left the organization, and became an outstanding businessman. At this time, he met Meidao again. The romance began...