Lin Xiaoxiao is an upbeat, optimistic girl who accidentally delivers a love letter to the wrong person and is forced to sign a “tyrant’s contract” with the cold and ruthless campus king, Mu Lingye. She thinks her life has hit rock bottom, but as she pushes back and gets to know him, she unexpectedly discovers the lonely heart hidden beneath his tough exterior. Even more shocking, an unexpected union between their families forces them to live under the same roof. As they go from bickering to falling for each other, they face the complicated feelings surrounding Mu Lingyu, his older brother, and the warm but challenging test of family life.