Kim Je-ha (an alias) is a former mercenary soldier for the PMC Blackstone. While in Iraq, he gets framed for the murder of his lover Raniya, a civilian. As a result, he runs away and becomes a fugitive. He returns to South Korea and by chance is offered work as a bodyguard by Choi Yoo-jin, the owner of JSS Security Company and wife of presidential candidate Jang-Se joon. He accepts the job in exchange for resources that he needs to get his revenge on another presidential candidate, Park Kwan-soo, who previously ordered Raniya's killing. Je-ha is assigned to guard Go An-na, the hidden daughter of Jang Se-joon whose life is always threatened because of Yoo-jin, her stepmother. An-na, who has been a recluse and lonely all her life, starts relying on Je-ha, who shows concern for her and protects her at all costs. They slowly fall in love, causing Je-ha to be torn between having to work with his ally, Yoo-jin, to enable him to take revenge on Park Kwan-soo and protecting his new found love, An-na, against his own ally.
Another key protagonist is Choi Yoo-Jin's half brother, Choi Sung-won, the son of her father's mistress and eventual second wife, who is his half-sister's fierce rival. Plotting with Park Kwan-soo, he eventually causes the deaths of Jang Se-joon and Choi Yoo-jin but later pays for this with his life at the hands of Choi Yoo-Jin's devoted (and ruthless) assistant Kim Dong-mi. Je-ha achieves his goal of revenge, with Park hanging himself for his atrocious acts and Je-ha clearing his name. The series ends with Je-ha and An-na embracing in a foreign country, with An-na asking Je-ha what his real name is and Je-ha about to reveal it.
