There were days where Kaley Cuoco would cry herself to sleep while making The Flight Attendant. The California native - best known for playing Penny in hit sitcom The Big Bang Theory - is an executive producer on the thriller series and also plays the lead role, Cassie.
She optioned the book on which the show is based - by New York Times bestselling author Chris Bohjalian - a few years back, because she loved how dark it is.
But she says, "I also wanted to bring my quirky, comedic side to it, and possibly create a tone that was unique."
And it was a scary process, hence the tears, because she knew viewers would judge her choice of project, especially coming off a successful show like The Big Bang Theory.
"I was taking a risk, because I don't believe in my heart that someone would have hired me to play this role," elaborates the 35-year-old, who started acting as a child and had her breakthrough role aged 16 with ABC sitcom 8 Simple Rules.
"I could have auditioned and I might have even given the audition of my life. I don't think someone would have given me this role. So, I wanted to prove that I can actually do more and that I love it. And it was a risk that I'm glad that I took.
"But, yeah, I was pretty sick to my stomach the night before the show aired just because it was my baby. I started this thing so long ago and you want everyone to like your baby."
Cuoco, who is married to professional equestrian Karl Cook, has this effervescence that means she often does not finish her sentences; suddenly, she is already on to her next witty, candid thought.
It is this energy and sense of humour that she brings to The Flight Attendant - an eight-part series about how an entire life can change in one night.
Cassie, a flight attendant, is on a work trip when she finds herself waking up after a big night out in the wrong hotel, in the wrong bed - and she realises the man lying next to her is dead. She has no idea what has happened, but is determined to find out.
The darkly comic show proved to be a hit in the US, where it debuted last November. It was quickly renewed for a second season and also received nominations at this year's Golden Globe Awards, including Best Performance by an Actress in a Television Series, Musical or Comedy, for Cuoco.
This resulted in the star posting some brilliant pictures on Instagram, showing her attending the awards ceremony, which took place at the end of February, virtually from home.
"My Golden Globes was getting drunk and eating cake and pizza with my family in Oscar de la Renta," she quips. "It was awesome. I couldn't have asked for more."
What was it exactly that drew Cuoco to the role of Cassie?
"What I love the most about her is she is very reactive. The world is spinning around Cassie.
"And, as an actor, I am incredibly reactive. Like, I'm not a prepared sort of a person, so it was great for me, because I was just myself.
"I was reacting to what amazing Zosia (Mamet, who plays Cassie's best friend, Annie) was doing and this murder and, 'Oh my god, the police are after me and the FBI.' Like, these were all reactive moments, until at the end where she's like, 'I need to take control'. It's an actor's dream.
"Also, I feel like I had multiple personalities. I mean, I got to play every emotion.
"At one point, we had been doing all these emotional scenes for three weeks. I'm like, 'Are people gonna be sick of me looking like that?' It was just constant torment on my face."
It makes sense when you realise some of the themes The Flight Attendant explores; trauma, dependency on alcohol and facing demons from childhood.
"I wanted to make sure that the alcohol was not the funny part," adds Cuoco. "Yes, she was a fun person to party with, but you see pretty early on that there is something else; it's all bubbling and it's all beneath and it's about to explode.
"She's a functioning alcoholic. This is not someone who's slurring in the streets all day long.
"This is someone who literally gets by because she is drinking sips of alcohol all day long. She has a career, she has great friends. But deep down, she is so struggling inside."
It is certainly a different type of comedy from The Big Bang Theory, which focused on a group of scientists and their love interests and came to a close in 2019 after 12 seasons.
Cuoco is reflective as she addresses how, particularly when shows have aired for such a long time, there is an idea that its cast might get pigeonholed.
"I used to laugh because I was like, 'If I'm typecast as the girl next door in a sitcom for the rest of my life, I feel like that's the best thing that could ever happen to me'. I never fought that feeling.
"And so, going into The Flight Attendant, I was not trying to be like, 'Let's pretend The Big Bang Theory never happened, I'm going to be this new actor'. It wasn't like that at all. In fact, I actually thought I would do a sitcom again.
"The Flight Attendant was just something that was the right project at the right time, but it wasn't about getting away from it."
She follows this by sharing what has been happening since her latest project aired across the pond.
"I've been called the newcomer recently, which is hysterical. All of a sudden, because I was like, 'I've loved everything I've done', they've erased the past that I had and I'm like, 'Does anyone remember I was on that sitcom for 12 years, like six seconds ago?' Nope.
"All of a sudden, they're like, 'Look at this newcomer on the scene'. And I'm like, 'I've been here for 30 years!'"
Well, let's hope Cuoco is on the scene for the next 30 years, too; there could even be more of The Big Bang Theory on the cards.
She says she would "absolutely" be up for filming a reunion, much like the Friends cast are set to do.
"I hope that our cast would be down for that some time in the future. I'm ready for that, any time."
The Flight Attendant, Sky One, Friday, 9pm