Every summer literally millions of vacationing tourists flock to Busan City on the East Coast of Korea. Their main destination is the idyllic, picturesque and popular holiday resort known as Haeundae Beach in search of sun, fun and romance. But geologist Kim Hwi has more legitimate reasons for being in Busan City. Despite being officially denied by the Disaster Prevention Agency, Kim is convinced that Haeundae beach is about to be hit by a mega-tsunami capable of obliterating anything that stands in its path. As Kim's worst fears are confirmed, Busan City is thrown into a storm of death and destruction.