A long time ago the pegasus Trusty Harp died. No one remembers her anymore and everypony in Equestria has forgiven the one responsible for her death his sins. Everypony except for one.
After spending thousands of years wandering all over the world in search for knowledge and power he finally returns to seek vengeance only to realize that his sworn enemy has changed. Questioning the purpose of his journey - of his live - it is up to the Mane Six to show him that he still can find happiness in his live.