In 1983, high school teacher Ji-hwan is attacked by a pickpocket. In 2015, homicide detective Gun-woo is shot during a chase and loses consciousness. Both men are taken to the same hospital in different time periods, and both their hearts stop and miraculously start again at the same time. A mysterious force binds them together, allowing them to see through each other’s lives in their dreams. Soon realizing that the women they love strikingly resembles each other and that they are in fatal danger, the two men must team up to trace the past and change her destiny.

Set in 1969 at the end of the Vietnam War, elite officer and war hero Colonel Kim Jin-pyeong is about to get promoted to general. He is a constant subject of jealousy, with the commander for a father-in-law and a beautiful wife. But in truth, his affection for his wife has subsided and he is suffering from post-traumatic stress disorder from the war. One day, Jin-pyeong encounters Ga-heun, the wife of one of his captains, and falls into a fatal and obsessive love affair that forces him to give up everything he had achieved.