Set sometime in the near future, South Korea and North Korea's relations have blossomed. The two countries have co-built a development station for methane hydrate off the coast of North Korea. Scientist Seo Myung-Joon (Hwang Jung-Min) from South Korea is in charge of the project and works closely with scientist Lim Jin-Jae (Kim Jung-Eun) from North Korea. Other technicians and researchers from both countries work under them at the development station.
During this time, North Korean leader Kim Tae-Sung (Seo Tae-Hwa) visits South Korea for the first time after becoming the North Korean leader. The president of South Korea Kang Dae-Hyun (Lee Soon-Jae) and North Korea leader Kim Tae-Sung watch a game between the inter-Korean team and the Australia team at the preliminary rounds of the World Cup.
Meanwhile, hardliners in North Korea, Jo Kook-Cheol (Jung Sung-Mo) and the military, carry out a military operation while their leader is in South Korea. The North Korean military relocate near the Korean boarder.
At the development station, the technicians and scientists work together peacefully, but there is still tension. Lim Jin-Jae receives an order to steal the core technology behind the operation. Min Dong-Ki (Kwak Hee-Sung) pushes her to carry out the order, but Lim Jin-Jae turns down the order. Lim Jin-Jae and Seo Myung-Joon first met 10 years ago and fell in love. They then reunited 2 years ago and discovered that their feelings are not so easy to forget.