体育经理人在贤(柳演锡饰)是个相当玩世不恭的青年,他在釜山高速列车KTX上第一次见到了秀晶(文彩元饰)就对其一见钟情,性格直率不羁的他提出要和秀晶谈一场一天的恋爱。秀晶是一个不愿意给男人任何可乘之机的“铁壁女”,面对在贤的各种无理要求她相当恼火,而在贤却决心要在24小时 内得到秀晶的心,这样一对想法完全不合拍的两人从此展开了一场爱情拉锯战。Soo-jeong has been dating with her boyfriend for 10 years, but their relationship isn't going so well. In the day of her business trip, she finds out that her friend is getting married with her first love, so she starts to feel weird and has some thought. On the train, she sits next to Jae-hyeon who is a womanizer, he feels attracted to her and tries everything to make her fall for him. They will share the trip to Busan together and know each other better.