During King Sombra's reign over the Crystal Empire, Mother's Day has been little more than a holiday to dismiss as no longer important in his life. Now, facing a destiny-altering decision that may cost him his iron-hoofed grip on the Empire, he has to face the fact his pony half needs and still wants the advice of a creature who not only leads the most feared race in Equestrian history, but also happens to be his mother.