So what mission is so important that it brings the aging head of The Bureau of Paranormal Research out of his office? It seems that one of the demons that the professor vanquished when he was a much younger man (a time that pre-dates both Hellboy and The Bureau) has decided to rear its ugly head again. Well, to be fair, it isn't an ugly head at all. A vampire and head-priestess of the goddess Hecate is being resurrected and this eternally young looking creature is looking for more blood.
Its up to Hellboy (Ron Perlman), Liz (Selma Blair) and Abe Sapien (Doug Jones) to not only get rid of the reborn vampire, but also take down a slew of demons, minions and even Hecate herself. Of course, the trio believes they are going to have to watch after their mentor (yes, even John Hurt reprises his role in this movie) as well, but it becomes pretty obvious that he shouldn't be counted out of the fight yet.
This film is actually two storylines mixed together. One story is in the present following the Bureau task force as they try to stop the ancient castle from bringing back its bloodiest owner, and the other follows the young professor as he attempts to stop the priestess the first time. On top of that, the flashback sequences are done in reverse order (a la Memento). At first this was a bit confusing, but when I realized what they were doing, it was very interesting to see what led up to the Professor taking a local priest with him, who the vampire's final victim was and how she got pulled into the priestess' trap.
This two-story style works pretty well because as the team runs into locals that the Professor knows (like the aforementioned priest), it is closely followed by a flashback that connects a conversation the present-time characters had and clears up some of the more interesting mysteries.
I found that this film's backstory approach, as well as the chance to see Professor Broom out in the field, really makes this animated feature the better of the two. I would recommend it to any Hellboy fan, or anyone just looking for an animated film to watch. Since this adventure takes place before the live action flick, you don't even need that movie for background.