While chatting with Margot Robbie earlier today about her neon-drenched noir "Terminal," we had to bring up one of the projects on her plate that fans are most clamoring for -- the untitled Harley Quinn spin-off.

Our first question was about how important it was to her, since Robbie will be both starring and producing the movie, to secure director Cathy Yan for the Harley Quinn spin-off.

"It was very important," Robbie explained. "I've been working on this for three years now and, from the beginning, I wanted to make an R-rated girl gang film and we needed a female director."

She then elaborated on the process. "The best director always wins, whether male or female, it's more about who understands the character the best. But given how few opportunities female directors get, particularly on these big budget films, I thought it was our duty to put more effort into exploring female directors than male ones," Robbie said. "Definitely not to exclude male directors, but put more effort into exploring female directors. So we looked at both male and female directors and Cathy was the best."

Robbie said she wanted an "authentically female perspective" for the sequel, which will be written by Christina Hodson, who wrote 2018s upcoming "Bumblebee" movie. Hodson also stepped in to replace Joss Whedon on the "Batgirl" film.

We were also curious as to why this version, instead of some of the other potential spin-off ideas, gained traction over such concepts as varied as a straightforward "Suicide Squad" sequel -- or one based on the "Gotham City Sirens" comic book.

As it turns out, it was the only version Robbie wanted to make.

"I pitched it to her actually," Robbie told us. "I said, 'I want to make a girl gang, R-rated film that Harley is a part of.' And we started working on it from there. Meanwhile, over the course of the next few years, the studio was exploring other Harley Quinn spin-offs. But I was not a part of those versions, I was always focused on this one with Christina."

Robbie went on: "I know that they were exploring 'Gotham City Sirens' with David Ayer, and I know they were exploring a Joker and Harley Quinn movie, and they were exploring doing I don't know what else. I wasn't a part of those. I was focusing on this. I kept presenting it to the studio until they felt it was at a point where they were ready to do it. And now we're all in."

While you wait for the untitled Harley Quinn spin-off, be sure to catch Robbie in the super cool "Terminal," in theaters and on VOD Friday.