Tian Sanqi, who has lived in Taoyuan City Yizhuang since childhood, has a cheerful and lovely personality, but has a strange hobby. She likes to perform autopsies and solve cases. She is a skilled female coroner. Sanqi and her childhood playmate, the little brother, used to accompany each other and spend a lot of good times together, but later they were separated for many years because of the strange disappearance of the little brother. For an ignorant promise in childhood, Sanqi vowed to find true love and marry him, but who is the childhood sweetheart? On the way to find the little brother of true love, Sanqi accidentally bumped into and flirted with many "suspected" target figures, either sweetly sprinkled sugar or tit-for-tat, causing many ridiculous things, and even met many partners with different personalities. The group was "accidentally" involved in many unsolved cases that occurred in the local area. With in-depth investigation, everyone found that these cases were closely related to the disappearance of the little brother that year! A shocking conspiracy that lasted for more than 10 years gradually emerged. The group of young people each showed their strengths and worked together to thwart the conspiracy. They gradually realized the true meaning of friendship and love, and continued to grow in the search for true love and uncovering the truth, full of youthful positive energy.