Caustic Shift, as the ponies know her, Is a 20 year old changeling who escapes from the hive when her father mysteriously leaves without a trace, and her mother seems to be hiding something. She ventures out in search of a new life, and any clues to her father's whereabouts, much to her mother's disagreement. However, when she makes it into Equestria, she realizes that she is being looked for as well...