The melodrama "Mother-in-Law's Diary" tells the story of the challenging lives of three friends. Lena's son brings home a girl named Nyusha and announces his decision to marry her. Sonya endures humiliation from her mother-in-law and is forced to reconcile with her lazy husband. Nata, a strong and independent businesswoman who is convinced she will never marry, meets a man. Each of the friends wants to find happiness, but in order to achieve their desires, they must overcome all the difficulties that fate has in store for them.