孟裴青、邵青、路亦青，是沒血緣卻勝似親兄妹的青梅竹馬，一起讀書玩耍，本以為會一起長大，不料路家父母意外身亡，被警察草草以夫妻口角失手殺人結案。 同時，撫養孟裴青的祖父母去世，在中國另有家庭的孟父回來處理喪事，並將孟裴青帶回中國，三人從此分開十二年。 路亦青被邵青父母收養，但邵母因過去拆散路母與邵父而家暴路亦青，路亦青成為女警後離開邵家，她想查父母舊案卻不得其法，反因處理家暴案件遭停職休假。 她回老家時與孟裴青意外重逢，確認彼此心意後，竟一起在夢中回到二十年前，她在夢中改變過去，隔日睡醒現實竟跟著改變，她決心與孟裴青阻止父母雙亡的悲劇。 兩人發現邵母夥同警官表弟下藥設局，拍下路母邵父不雅照，表弟以此威脅同為警察的路父不得檢舉他受賄，兩人起爭執動手，幸好被孟路兩人阻止。 成功救下父母，但路亦青終究要面對真相──孟裴青早已車禍身亡，陪伴她的是個鬼。她決心再次回過去挽救愛人性命，即便要換她犧牲性命……

Meng Pei-Cing, Shao Cing and Lu Yi-Cing grew up together in a small town. They were very close and used to study and play together all the time as a child. They thought their friendship would last forever, but one day, Lu Yi-Cing 's parents died accidentally, despite there being a lot of suspicion about this case, the police decided to close this murder case with the conclusion that Lu Yi-Cing 's parents died from an accident while they were fighting. In the meanwhile, Meng Pei-Cing 's grandparents passed away, and Meng Pei-Cing 's father came back to the town from China for the funeral, then bought Meng Pei-Cing back to China with him. Meng Pei-Cing, Shao Cing and Lu Yi-Cing were separated since then. 　 Lu Yi-Cing was adopted by Shao Cing 's family after Lu Yi-Cing 's parents' death. Lu Yi-Cing suffered abusive behaviour from Shao Cing 's mother who felt resentful because she interrupted Lu Yi-Cing 's mother and Shao Cing 's father's relationship back then. Lu Yi-Cing left home after she became a policewoman. Despite Lu Yi-Cing 's willingness to find out the reason caused her parent's death; she was asked to take leave from work because of her inappropriate approach to a domestic case she was working on. 　 Lu Yi-Cing went back to her hometown and met Meng Pei-Cing again. They fall in love and back to the time twenty years in their dreams together. They changed the scenes that happened in the past. The reality has changed too when they wake up the next morning. Lu Yi-Cing and Meng Pei-Cing decide to stop their parents' tragedy. 　 Lu Yi-Cing 's parents were saved by Lu Yi-Cing and Meng Pei-Cing, but Lu Yi-Cing had to face one fact – Meng Pei-Cing is a ghost, he was dead from a car accident. Lu Yi-Cing wants to back to the dreams to save Meng Pei-Cing 's life as she did for her parents, but only this time, she needs to sacrifice her own life in exchange for Meng Pei-Cing 's.