SPOILER ALERT: Do not read if you have not yet watched “Locke and Key,” streaming now on Netflix.

In March 2018, Carlton Cuse found himself faced with a TV showrunner’s nightmare. He’d been working for nearly a year on “Locke and Key,” an adaptation of Joe Hill’s best-selling graphic novel series about the Locke children, who move into their elaborate family mansion after their father is murdered, only to discover a suite of magical keys that plunge them into a macabre supernatural battle between good and evil. Andy Muschietti, hot off his blockbuster Stephen King film “It,” had directed the “Locke and Key” pilot and seven scripts were already completed.

Then Cuse got the news: Hulu was passing on “Locke and Key.” After an intense campaign to save the show, Netflix officially rescued it in July, but with a helluva catch: The streamer was scrapping Hulu’s version outright. Cuse was partnered with co-showrunner Meredith Averill (“The Haunting of Hill House”), and had to start all over again with new scripts, a new pilot and almost entirely a new cast.

“It’s hard,” Cuse tells Variety, “but ultimately, I love this material so much that the desire to bring this thing to the screen and figure out how to make it work and to get this in front of audience was” still there.

“At that point, it was really time to not think about the past but think about the present,” he continues. “I just tried to approach it with fresh eyes and an open heart and a strong desire to see this story get made.”

Cuse and Averill did indeed get it made. After a serpentine path through half of Hollywood — a TV pilot for Fox, a screenplay for Universal — “Locke and Key” finally debuts today on Netflix in a substantially different shape than the Hulu version.

“The Hulu version was a little more on the horror axis of the comics,” says Cuse.

Muschietti had to bow out to direct “It: Chapter Two,” so Michael Morris (“13 Reasons Why”) took the reins for the Netflix pilot, which Cuse says leans “more into the fantasy elements of the story.”

“Obviously ‘Stranger Things’ is a big success for them,” he says. “The fantasy elements was something that as Meredith and I started working on it we felt was really true to the comics and something that we really embraced as storytellers.”

In doing so, however, Cuse and Averill wound up making major changes to the structure and tone of Hill’s original comic — with, they say, Hill’s blessing.

“When you’re telling a story and you start pulling threads, everything changes and unravels and moves,” Cuse says. “The more we started shifting the tonal axis of the show, the more the storytelling changed.”

The first big change was the decision not to start the story with the murder of Locke family patriarch Rendell Locke (Bill Heck). The concern, Cuse says, is that doing so would have suggested to the audience, “OK this is going to be a very gruesome, violent, more horror-tinged version of this story.”

Locke and Key Netflix

Instead, the murder is parsed out in flashback as bursts of fractured, traumatic memory. “[We’re] leading with the mystery — letting the audience lean in and wonder what’s happened to this family,” says Averill. “We love the idea of teasing out that these characters in these scenes that we might not necessarily know what they are.”

At the same time, Cuse and Averill embraced the magical elements of the show to explore the emotional toll Rendell Locke’s death has on his family, like when Rendell’s daughter Kinsey (Emilia Jones) uses a key that allows her to enter a vast representation of her own mind — and interact with personifications of her emotions.

“One of my favorite stories from the comic and from our series is about Kinsey has this opportunity to remove her fear [from her mind],” says Averill. “We get to see her do that and live fearlessly, and then some very big, dangerous consequences come out of that. Being able to tell that story with the use of the keys is exactly, I think, the sweet spot of where our show lives.”

Cuse and Averill also altered the order of how the supernatural saga unfolds in “Locke and Key,” like the order in which the various magical keys are discovered, and when the audience gets clued into Rendell’s mysterious past. One big change occurs on the show’s first episode, when the main villain, a demon known as Dodge (Laysla De Oliveira), is released from her captivity on the Locke property — something that doesn’t happen until well into Hill’s graphic novel.

“Comics is a very different form,” says Cuse. “You have a limited number of panels, you have a limited number of words per panel. The rhythm and the flow of it is very specific and different. It felt like we could take a lot of the same elements, but re-ordering them would just help the way that we chose to tell the story. Joe really embraced and actually participated in those changes.”

The results have pleased Netflix enough that even though “Locke and Key” hasn’t been officially renewed, Cuse and Averill are already in a writers’ room for Season 2. Beyond that, however, Cuse and Averill say they’re not sure how many seasons it will take to adapt Hill’s graphic novels — in part because he’s still working on them.

“The world of this show is still very much alive in [Joe Hill’s] brain and as a participant in the making of the series, he’s very much a part of these same conversations about how long should it run, and what stories do we want to tell,” Cuse says. “By the time we finish writing the season, we’ll have a better idea of we want to do in this world. It definitely has two seasons worth of storytelling. And probably a little bit more.”