I ask Witherspoon how rare it is to see a female character like Maggie, who is not about her sex appeal but rather about her particular skill.
"Growing up, I always saw James Bond movies, my dad was obsessed with them, but I was like, why are [the girls] all in bikinis, and I don't understand what that's got to do with solving the crime," she replies.
"If I was going to do a thriller, I wanted the woman to be at the centre of it. I wanted her to have a unique skillset everybody in the world wanted, but she didn't even realise it, and that she doesn't have to shoot guns or punch bad guys. She's actually just very smart and very intuitive and an incredible surgeon."
But the film industry still has further to go in creating such roles for women, Witherspoon suggests.
When I ask whether Hollywood still suffers from a lack of strong female leads, the A-lister says: "I always see the gap, I see the white space.
"I started Hello Sunshine in 2011 because I just wasn't seeing complex storytelling for women in the movie space.
"So, in a way, I was just taking the relationships I've had from 30 years of being an actor and just helping shine a light on women who were ready for those opportunities."
Entertainment journalist Lauren Morris believes Witherspoon has been "quite clever" in the way she's built her business empire.
"She has her book club, where she publicises books, often centring female stories. Then she has her production company, where she adapts it for TV or film, and she often stars in it herself too," she says.
"It's a good business model and it's working well for her."