Brian McGreevy has had a crash course in television production as the writer not only adapted his popular novel, “Hemlock Grove” (along with writing partner Lee Shipman), into a series for Netflix, but also served as an executive producer.

Losing an early battle to shoot the series in his home state of Pennsylvania – where the story is set – ultimately ending up in the more production-friendly Ontario, the 29-year-old got used to the compromises one must make to turn a novel into 13 TV episodes (which are all available on Friday).

“Myself, as the creator of the material, tends to want to make the argument to do things that would cost too much or take too much time,” McGreevy tells TheWrap. "Whereas myself as executive producer actually has to work within the given constraints."

Also read: 'Hemlock Grove' Red Band Trailer Is Full of Blood, Sex and an Awesome Werewolf Transformation (Video)

He points out examples such as wanting to use a song he thinks is perfect for a particular scene only to find out it would cost their entire music budget. Or, wanting to fill a shot with people, which means the time and money of casting extras that the production doesn’t have.

“When you’re writing a book, obviously, there’s no limitations to the setting,” he says. “You’re not dealing with central casting.”

“Hemlock Grove” kicks off with the brutal murder of a teen girl and concentrates on Roman (Bill Skarsgard) – who’s probably some kind of supernatural being – and Peter (Landon Liboiron) – who’s most definitely a werewolf – and their complex families, as well as their possible involvement in the crime.

Also read: 'Hemlock Grove' Co-Creator Embraces Show's 'Big, Pulpy, Gothic Soap Opera' Elements

Whether you’ve already read the novel or jumping headfirst into the Netflix adaptation, McGreevy reveals six things you can expect from “Hemlock Grove.”

Warning: Mild spoilers ahead.

1. Expect a couple major deviations from the novel. “I would say that plot-wise it’s really similar with the caveat that there’s one or two major deviations that are a bit of a curveball. And, also, adapting a 300 page book into a 13-episode series requires a fair amount of expansion and invention.”

2. A slow burn. “There’s some stuff that happens out of chronology and I think people will be pleasantly surprised by ultimately the scope of the series. We wanted to slowly unravel.”

3. Keep an eye on Godfrey matriarch, Olivia (Famke Janssen). “The town of Hemlock Grove wouldn’t have been built without the Godfreys. They are an old family. They are a very moneyed family. There’s a lot of dark skeletons in their closet. And then, there’s this very mysterious event happens 20 years ago, which was the introduction of the Olivia into this family, which has completely fractured the company. It’s fractured the family relations and the question of where she has come from and what she wants is one thing that is really driving and underlying the season.”

Also read: Netflix's 'Hemlock Grove' Trailer Teases Sex, Murder and Monsters (Video)

4. The secrets of Shelley Godfrey (Nicole Boivin). “Shelley gets revealed a little earlier than Olivia. There’s not especially that much of a mystery behind Shelley. As in, it’s not really a big reveal. In terms of the execution [of Shelley’s look], that’s an example of if we’d stuck with the dramatization of that character in the book it probably would have been the entirety of our special effects budget. But, that’s when it’s Eli Roth‘s job to come in and be inventive.”

5. Season 1 spans the entire novel. “We definitely used up everything from the novel in the first season, because we wanted to structure it so if it was one self-contained story it would leave the audience satisfied at the same time keeping the door open for these storylines.”

6. So, what’s left if there’s a Season 2? “[Viewers will] find that the characters of Roman and Peter are left at pretty decisive moments in their life, which will have a big impact on the men they’re becoming. And also, there’s a lot of freedom of creativity in exploring future storylines because we f—ing kill half the cast.”