A romantic melodrama that depicts the lives of a young man and woman who begin to discover their true feelings whilst playing the dangerous game of love. The show is based on the classic 18th century French novel Les Liaisons Dangereuses by Pierre Choderlos de Laclos.Student president Choi SuJi, Kwon SiHyun eldest heir of the JK Group, and casanova Lee SeJu have been bestfriends since childhood. SuJi's current boyfriend, Lee KiYoung humiliates her and her mother for trying to use him to climb up the social ladder and breaks up with her. As the last straw, when SuJi's mother and SiHyun's father announce their engagement, the trio devise a plan to hit two birds with one stone.
Eun TaeHee is a hardworking female college student who no longer believes in love after watching the demise of her parents' marriage. SuJi finds out that TaeHee is KiYoung's first love, and asks SiHyun to seduce TaeHee and then break her heart, as a way to prove his loyalty to SuJi. After proving which, SuJi and SiHyun will get married to prevent their parents from doing so themselves.
However, all does not go as planned, when SiHyun and TaeHee begin to actually fall for each other. The strain this puts on the trio's friendship, TaeHee's reaction after seeing their true faces and KiYoung's thirst for revenge make up the rest of this drama.