According to New York Times best-selling thriller author and screenwriter Gregg Hurwitz, he and his writing partner, Philip Eisner, wanted to write a different kind of dark thriller.

“It starts off as a revenge-thriller and there’s a turn that seems to come out of nowhere. We also wanted to do something character-driven,” Hurwitz says. “It’s about a man named Cooper who is avenging his wife’s murder. But the key relationship is between Cooper and his daughter. It’s part mystery, too, as the audience tries to piece together what happened and why.”

The thriller Hurwitz and Eisner concocted is Sweet Girl, which was recently bought up by Netflix and will star Jason Momoa as Cooper, the husband who vows to bring justice to the people responsible for his wife’s death. Momoa will also produce the film, which reunites him with producer Brian Andrew Mendoza (Frontier, Braven), who is making his feature directorial debut with Sweet Girl.

The concept was initially Eisner’s idea, which he shared with Hurwitz over lunch in L.A.

“We had a luncheon and talked through the story. Phil came to me, he had the idea for it, and I told him the stuff that I didn’t like, the stuff that I thought was brilliant, and I said to him, ‘Look, if I were the one who was writing it, I would do this and that was the 90 degree turn,” Hurwitz says. “At the end of the lunch, I asked if he wanted to try writing it together because we work well together, and we talked it out. We agreed to do it.”

Hurwitz and Eisner met years earlier on a polish job for a sequel to The Thomas Crown Affair from a script by John Rogers.

“Phil and I pitched to write the heist scenes, and we were assigned together. The project was neither one of our babies, so we were able to work more flexibly,” Hurwitz shares. “We were able to just walk around and plan cool heists all day that would work with the script. We got along really well, so since then, we’ve shared our work with one another and take a read on what we are working on. He gives me notes, I give him notes.”

Hurwitz says the process on Sweet Girl—from concept to sale—took two years while he and Eisner worked on their respective other projects simultaneously, which included Hurwitz pumping out two novels. When it came to writing together, Hurwitz says it consisted mostly of sitting down separately and writing a block of pages. “He would take a pass, I would take a pass, and we would email a bunch of Final Draft documents back and forth.”

While Hurwitz says both he and Eisner usually write alone, the experience was an enjoyable one. “The thing with Phil is that he’s such a professional. We have both been doing this a long time, so there’s no ego, no sensitivity, so we could be very blunt with each other and direct on what doesn’t work. It was all about being concerned with the best scenes; the best narrative drive.”

What was key for both writers was that the script wasn’t a generic thriller, but about the character. “There are so many thrillers out there all the time, so it was important for Phil and me to write a movie like The Professional or Seven that had an iconic feel to it. Even if they were dark, they were really dedicated to character,” Hurwitz says.

He also says they took the script to producers early. Jeffrey Fierson from ASAP Entertainment jumped on board, and Momoa, who also happened to be their top choice for the role of Cooper.

“We were looking at Momoa as a potential lead, and [Brian] Mendoza had the perfect feel for the script. He has a real artistic sensibility; a lot of heart to him. It was important to us that this script wasn’t a generic thriller, but strongly character-based. Then we went to Netflix, and the rest is history.”

This is Hurwitz’s third spec sold. His previous spec was the movie The Book of Henry, and he sold another unproduced spec to Warner Bros. The author of the “Orphan X” thrillers keeps busy with novels, movie assignments, and various TV work.

When it comes to writing and the nature of the finicky beast that is Hollywood, Hurwitz’s advice to aspiring screenwriters is simple: “You have to be someone who actually likes to write. If you love doing the thing itself, then the agent, the sales, the career is all gravy. But that’s not the point. The point is loving it and devoting the time to do it.”

He adds, “If you write 20 screenplays and none of them sold, put that effort into writing one screenplay and making it that good. It’s all about polishing. Don’t get ahead of yourself too much with business. If you write something that’s the story you want to tell, then the business will take care of itself for you.”