An old threat returns to destroy equestria as well as the princesses and the knight who stopped him but the knight has been missing for thousands of years.
The knight had helped the princesses find the tree of harmony and defeat discord and he was the one who locked King sombre away with the help of the princesses. But what the knight is most famous for was fighting and defeating the demon Lord Darkfire who he locked away with his astral magic but the magic seal has been broken and with no knight to defend equestria all hope seems lost.