On an exceptional morning, Ding Lin, a girl nicknamed "Sparrow" who lives alone, picked up two of her classmates: an autistic young man who attempted suicide, and an unruly young man who ran away from home. Due to a strange combination of circumstances, Ding Lin's best friend Xue Yi also moved into her small sparrow nest. The four characters have completely different directions. In this hot summer vacation, the drama begins to unfold.