It begins with a crush that turns into a romance between a physicist and a third year university student after they met because of a misunderstanding. Mu Chenghe (Zhang Chao) is getting his PhD in physics at Donghu College. When he was suddenly tasked with proctoring a college-level examination, he mistakenly accuses third-year student Xue Tong (Li Tingting) of cheating. Despite getting on each other's nerves at first, their interactions blossom into a schoolgirl's crush and a mutual attraction. During her college days, Xue Tong meets three roommates - the icy beauty Zhao Xiaotang (Sun Jialing), the bubbly Bai Lin (Zhang Zhang) and the gentle Song Qiqi (Deng Xin). The four girls with different personalities become lifelong friends. Over the years, there are people that are gone forever and things that can no longer be changed and these days become an exclusive memory.