Yeong Jae, Ha Eun and Chun Hee have been friends for 15 years since high school. Yeong Jae is the youngest of a fine hotel owner and she aims to sleep with 1203 men throughout her life. On the other hand, Chun Hee is an old-school minded high school teacher who has never had sex before in her thirty-something life. Wedding planner Ha Eun was in love with one man for 10 years but recently experienced the pain of losing both her man and work. Then one day, to celebrate their 10th year majority, they have a party of their own in room 1203 of Yeong Jae's hotel. The 3 girls' talk goes overboard, they end up making a bet; they have to meet a man and spend a hot night with him. They target the hotel bellboy Hyeon Soo who looks just like the guy at school all three of them used to like.