The upcoming animated release of Batman: The Long Halloween will consist of two installments, but now, we know that the second part will be a lot more violent than the first. The Motion Picture Association (MPA) has given part two of the Warner Bros. movie an R-rating, which means the movie has adult content. Interestingly, the first part of the double feature is only rated as PG-13, which means the violence in The Long Halloween adaptation is seemingly poised to escalate as it did in the original comic book story.

On the MPAs official website for movie ratings, the association justified the ratings of Part One of The Long Halloween "for violence, bloody images, language and some smoking." This is not so different from the notes left for Part Two, which receives the R-rating "for some violence and bloody images." It’s curious that two parts of the same product are rated in a different manner, especially when they seem to have the kind of content. A closer look at the Batman comics arc of the same name, though, might explain the reasoning.

The Long Halloween was originally a 13-issue Batman story published monthly between 1996 and 1997, written by Jeph Loeb with art by Tim Sale. when we think about story continuity, this arc is a direct sequel of Batman: Year One from 1987, in which Frank Miller and David Mazzucchelli redefined the nature of Batman as the broody and dark character we know today. These stories were designed as a way to breathe new life into DC Comics, and in the case of Batman, they also served to make way to a more violent approach to The Dark Knight. After Miller rewrote Batman’s origin in Year One, Loeb did the same to some of Gotham’s biggest villains in The Long Halloween, especially Two-Face.

While Year One focused on Batman’s struggle against criminal families and gangsters, The Long Halloween brings together some of Batman’s deadliest foes, such as Scarecrow, the Joker, Mad Hatter, Poison Ivy and the Riddler. More central to the story is Harvey Dent, a district attorney who turned into the villain Two-Face after having his face disfigured by acid during a court trial. The story of Harvey Dent, from attorney to villain, also represents an important moment in Batman’s history in comics continuity, when the vigilante stops fighting goons and starts his never-ending conflict against super-villains.

This is exactly what The Long Halloween is about, starting as a story about a mob war and a serial killer only to escalate to Two-Face's ascension and a long night for Batman when the newly formed villain releases all the inmates imprisoned in Arkham on Halloween. From regular crime figures to the biggest Batman villain, The Long Halloween becomes more violent with each issue, as if to reinforce the idea that Batman needs to adapt to enemies that are even more dangerous. This is the mythology the animated movie will explore, and the difference in ratings shows us that the adaptation is going to be faithful to the original story.

Batman: The Long Halloween recently announced its voice cast, which includes Jensen Ackles (Supernatural) as Batman, Josh Duhamel (Transformers) as Harvey Dent, and Troy Baker back as the Joker after Batman Unlimited and Batman: Assault on Arkham. Other voice cast includes Billy Burke (Twilight) as James Gordon, Titus Welliver (Bosch) as Carmine Falcone, Alastair Duncan as Alfred, Fred Tatasciore as Solomon Grundy, David Dastmalchian as Calendar Man, Amy Landecker as Barbara Gordon, Julie Nathanson as Gilda Dent and Jack Quaid as Alberto, with additional voices by Frances Callier, Greg Chun, Gary Leroi Gray and Jim Pirri. The late Naya Rivera voices Selina Kyle/Catwoman.