Tsunami, a popular vacation spot on the East Sea coast of the Korean penninsula, draws one million visitors to its beaches every year. Man-sik, a native of Haeundae lost his co-worker in a tsunami four years ago, but now he leads a simple life running a small sushi shop and is preparing to propose to his longtime girlfriend, Yeon-hee. Meanwhile, a tsunami researcher KIM Hwi discovers the East Sea is showing signs of activity similar to the Indian Ocean at the time of the 2004 tsunami. Despite his warnings, the Disaster Prevention Agency affirms that Korea is in no harm. Eventually, a deadly wave is coming with only ten minutes to spare. While the vacationers enjoying a peaceful hot summer day, a mega-tsunami is headed straight for Haeundae.