Lightning had just found out he is the son of King Sombra; what would Twilight and her friend think of him now? Will they would even stay friends with him?

The Mane 6 defeated King Sombra, and his son brooded in the abandoned castle of his father, plotting vengeance. Consumed by the need to see through the unfinished business of his father's dreams. He would do anything to finish off his revenge.

A festive evening at the Lightning mansion turns into shards when his lifeless body falls from the balcony. Since every guest is a suspect, it's up to Twilight and her friends to find out who, where, and how, before the killer does it again.