Despite hardships in life, Tang Yi Xun (Zhou Yi Ran) and Ye Hai Tang (Wang Ying Lu) have built a sweet, solid romance together. However, their relationship seems to have an end date, as Hai Tang disappears, leaving only unanswered questions behind. As Yi Xun searches for answers, he encounters a mailbox with a mysterious letter sent from Hai Tang. Yi Xun writes back, re-opening a line of communication between them. But Yi Xun soon learns that Hai Tang is separated by more than just distance, as they are also somehow separated by time. Can they ever find a way back together?