Won-Il used to be a promising swimmer like his championship swimmer father. After his father's death from a swim competition, where he was doing his specialty called "No Breathing", his mother also passed away.
Since then, he can never forgive his father and quits swimming for good. Living like there is no tomorrow with his easy-going attitude, Won-Il seems hopeless. When he is being dropped out of school, his father's longtime friend Jae-Suk drags him to get into a physical education high school to start swimming again.
There he meets his long-ago rival, Woo-Sang who was always overshadowed by Won-Il. With Won-Il's absence, Woo-Sang took up the first place and grew up to be the national swim star. He is completely opposite to Won-Il in that all he cares is winning. Woo-Sang is disqualified as national athlete by getting into a trouble and starts from ground zero at the same phys-ed school as Won-Il.
Won-Il's return is unwelcomed by Woo-Sang but Won-Il does not care. Then there is Jae-Suk's daughter, Jung-Eun who captures both Won-Il and Woo-Sang's hearts and reignites the rivalry between the two.
The two very different restless youths start on the swimming competition for the love and friendship which is in fact, the rite of passage to growing up.