LOS ANGELES - Whatever actress Kaley Cuoco did after The Big Bang Theory (2007 to 2019), it was always going to be a tough act to follow.

The sitcom made her one of the highest-paid actors in television, as she and her four co-stars took home a combined US$130 million during the show's wildly successful 12-year run and US$1 million (S$1.37 million) apiece an episode for the last five seasons.

But the 36-year-old chose an especially steep learning curve when she decided to both develop and star in her next big project: the thriller comedy The Flight Attendant (2020 to present).

The series - back for its second season on HBO Go - was a critical smash, picking up five Emmy nominations in 2021, including for best comedy series, writing and direction.

Cuoco - nominated for best lead actress in a comedy - plays hard-partying flight attendant Cassie Bowden, who in Season 1 woke up next to the dead body of a passenger she had spent the night with.

Unable to remember anything because she was blackout drunk, she tries to piece together the man's life and track down his killer - in the process facing some uncomfortable truths about her own past.

It was Cuoco who developed the project from the ground up through her production company, obtaining the screen rights to the 2018 novel of the same name.

"As The Big Bang Theory was coming to an end, my team was encouraging me to think about what was going to be next," she says at an online media festival. "I started looking at articles and books to adapt something, and as I was looking through upcoming books on Amazon, I saw The Flight Attendant. It was not available yet, but I read the little snippet."

She did not have much to go on, "but I knew it was going to be good", she adds.

"I know it sounds cheesy, but I got this really weird feeling, this chill. And I said, 'This is it.'"

Then it was a scramble to secure the screen rights.

"I called my attorney and the first question I asked was, 'Did Reese Witherspoon get the rights to this book yet?'" she recalls, referring to the Oscar-winning actress behind book-to-screen adaptations such as Big Little Lies (2017 to 2019).

"They said no, so I got lucky."

When she finally read the book, she realised this could be her next TV show. But she wanted to put her own spin on the character.

"The book was actually very dark, which I loved, but I thought maybe we could tweak it more into my voice and put some Kaley-isms in there," she says.

The show also had a tricky balancing act with the comedy and mystery thriller elements, along with darker themes such as alcoholism.

And it employed an unusual narrative device for when Cassie tried to remember the night of the murder: She would enter a "mind palace", an imaginary space in her head, to process what happened.

That idea, from screenwriter Steve Yockey, made everything click into place.

Cuoco says: "What was going to be the weird thing that made the show what it was? And for me, it was the mind palace. Because I didn't want the ghost of someone haunting Cassie, so how can we tell this in a different way."

But she admits that she and the rest of the creative team were not sure they could pull this off. "We had to feign confidence and be, like, 'This is the tone.' And the audience is either going to jump on board with that or not. You have to wholeheartedly believe it or they won't."

The Flight Attendant 2 is available on HBO Go.