Rudie was a member of a pack that was caught trying to burrow into Canterlot Castle. In the wake of their discovery he played a role in the deaths of four Royal Guards. Ever since the first day of his punishment he has been growing slowly distant and, according to his former pack, unstable. One day, he needed air; The result was him clawing his way out of a high security prison located under the Canterlot Mountain.

To find this highly dangerous criminal, Princess Celestia summons Gwyneth – a natural-born Equestrian Griffin of a disgraced line of inquisitors, detectives, and bounty hunters – to assist the Elements of Harmony in tracking him down.

As the days go by, the body count rises, but it doesn't look like Rudie's. Someone else is tracking him, and they're a grim vigilante. As the corpses are outted as serial killers and similarly sickening scum, with their victims in tow, it begins to look like Rudie doesn't have much time to enjoy his freedom. The mission becomes less about finding him for the safety of others and more about finding him for his own protection, but will Gwyneth and the others make it in time?