The story takes place in Haeundae, Busan, South Korea. In the 2004 Indonesian tsunami, the mistake of Captain Wanzhi (Sol Kyung-gu) led to the death of Yeon-hee's (Ha Ji-won) father. He felt deeply guilty and took care of this neighbor sister in every possible way. Gradually, the two secretly fell in love. However, Wanzhi's middle school classmate Wu Dongchun (Kim In-kwon) did not think highly of this pair of unfortunate couples. Wanzhi's younger brother Hengzhi (Lee Min-ki) is a lifeguard at sea. During an operation, he met the rich lady Jin Ximei (Kang Yi-won). The two made a lot of misunderstandings in their interactions. Virgin (Uhm Jung-hwa) promoted Haeundae to become an ambassador for the World Expo tourist attraction. She and her ex-husband, Jin Hui (Park Joong-hoon), a geologist at the International Marine Research Institute, have a daughter, but she has now found another lover. Dr. Jin was very depressed about this. At the same time, he found that the geological conditions of the East China Sea in Dama Island and Haeundae were exactly the same as the 2004 Indonesian tsunami. A rare and huge tsunami was approaching Haeundae, but the Disaster Prevention Agency did not take it seriously...