Can one night really change an entire life? In the case of Im Yoona, Yes. Im Yoona doesn't have the easiest life, with being poor, with having an evil stepmom and stepsister that'll do anything in their power to make sure her life is hell, with having a dad that's pretty much under the spell of them both, but she still has always remained nice, sometimes too nice to the point where she'd be what you would call a pushover. But behind all the bad, her life does have a glimpse of good. Yoona is still a straight-A student and has Ok Taecyeon in her life. Taecyeon is Yoona's PERFECT boyfriend, who is handsome, caring and would do anything and everything in his power to protect and help her. They're each others first loves. But after one night encounter with Cho Kyuhyun, an arrogant rich boy with a complex story, her life goes through some drastic changes that take her life in a seemingly new path. How will this path go?