Following the success of Netflix's drama House of Cards, the company is switching gears with its next original series, Hemlock Grove. Based on the book, executive produced and developed by Brian McGreevy and backed by Eli Roth, the horror show will get to show off Netflix's dark side.

That's a side that Roth is excited about exploring. Though fans won't see him make a cameo appearance in Hemlock Grove -- "We tried, we had one planned," he lamented -- Roth did tease during a roundtable interview at WonderCon Anaheim that the series will go to some dark, disturbed places. He said that their team treated Hemlock Grove as a 13 hour movie, and though it doesn't break Netflix's rules about showing too-graphic violence or sexual penetration, it still pushes the boundaries of how far traditional television will go pretty far.

"I had been asked for a horror series going back to Cabin Fever," he said. "I always thought, 'Well, what makes horror great is you can kill anyone at any time. Anyone can go.' And what makes television great is people love the characters and want to see them week after week."

Roth admitted that shows like The Walking Dead helped pave the way for a project like Hemlock Grove to exist, and also appreciated that McGreevy used the original origins of creatures like werewolves and vampires that inspired people like Mary Shelley and Bram Stoker in his story.

"Brian's imagination was so wild. He actually even started writing it before Twilight," Roth said. "We thought now we can actually film it in an adult way, that if we want to have sexuality and nudity, the sex scenes feel like real sex and the violence is real and we talked about our werewolf transformation, [executive producer and director] Deran [Serafian] and I, we wanted to do something that would be the signature moment of that series."

That signature moment ended up being the werewolf transformation in Hemlock Grove. Yes, Hemlock Grove involves werewolves and vampires and other supernatural creatures, but it's a very different beast from something like The Twilight Saga or Warm Bodies. Roth and Serafian, who was also present at the interview, said they looked at werewolf transformations in movies like An American Werewolf in London, The Howling and even Twilight to try to make theirs both derivative and original.

"We spent many, many nights just sitting there in Pittsburgh and all the different places we went to talking about this transformation. How do we make it nostalgic, so reminiscent -- because it's got to have that sort of Eli Roth vibe to it where it's slightly horrifying," Serafin explained. "We talked about this and we decided to break some rules. Let's have the sun not completely down and a lot of things that really sort of helped it. Eli was talking earlier that it's just like giving birth -- yes, giving birth, but having an orgasm at the same time."

Roth continued of the werewolf transformation, "It's painful. It's like someone having a really painful seizure. It hurts so much you can't even remember it, but you know it's coming but you want it to happen but this wolf bursting out and then it can eat the placenta -- and Darren's like, 'Yeah!' -- and then it can shake like a wet dog. We just started thinking about it as this violent thing bursting out of you and what that would really do."

McGreevy, his co-developer Lee Shipman and executive producer Mark Verheiden held a separate group interview where they gave their own take on the series. It turns out that McGreevy has three seasons of Hemlock Grove planned, though that plan could fluctuate if needed. He also teased that he'd like to see Netflix experiment with the traditional hour-long episode format in future seasons, and maybe change up his style of storytelling as a result of that.

McGreevy's Hemlock Grove novel was published prior to the TV series premiering on Netflix, and the writer used a lot of research to develop his story. "My Google search history was definitely very interesting," he admitted, saying he spent a lot of time reading up on biotechnology and archetypal psychology, specifically monsters. He and Shipman knew from the second House of Cards was announced that they wanted to make their show on Netflix, and enjoyed the fact they were able to write the entire first season up front.

That said, there were some changes made to the original story as they developed the TV series. The final product is not far off from the original Hemlock Grove concept, but characters like Kandyse McClure's Dr. Clementine Chasseur, Aaron Douglas' Sheriff Tom Sworn and Lili Taylor's Lynda Rumancek were beefed up because the actors playing them were so good. In fact, McCreedy admitted that they never intended to make Chasseur an attractive woman, but that changed when "the most beautiful girl on planet Earth" auditioned for the part. The same went for Bill Skarsgard, as he was the first person to audition for the role of central character Roman Godfrey and was so good at it that the producers didn't need to look for anyone else.

Expect the first season of Hemlock Grove to end on a cliffhanger, but also be comforted by the fact that Roth, McGreevy and the rest of the team have the whole series planned out. "It's a murder mystery, and by the end of it we're going to solve it, but there's also a much bigger macro story that leads into Season 2 and 3," Roth teased of the upcoming show.

Hemlock Grove's 13 episodes premiere on Netflix on April 19.