Seohae Shim and Donghae were high school sweethearts and were set to be to be married. But out of the blue, Donghae broke up with her, and to find out that he had cheated on her, with her best friend, Kyumi. Heart broken and angry, Seohae left the dorms. 

6 months later, Seohae arrives in Las Vegas to attend the wedding of Kyumi and Donghae. The next morning, Seohae woke up, with a hangover, , and a ring on her left finger. Freaking out, she looked to her left to see the one man that she hates the most... Park Jung Su.