Kendrick gets dangerously close to Lively, Golding in A Simple Favor

Director Paul Feig, helmer of female-centric comedies like Bridesmaids and Ghostbusters, switched genres and handpicked Anna Kendrick to be the star of his new mystery thriller, A Simple Favor.

What convinced the US actress to take the role of a vlogging mum who turns detective when her glamorous friend Emily (Blake Lively) disappears was the opportunity to examine women's friendships.

Kendrick, 33, said at our interview at the Crosby Street Hotel in New York City: "Women have such layered, complicated, confusing relationships, so it was great to have a chance to really explore that in such an exciting thriller."

On the surface, her character Stephanie Smothers has Kendrick's sunny personality, but there is a whole other side of her.

"She is upbeat and always seeing the bright side, so she can be a little insufferable. But I think there's also a real sadness to her because she's so lonely. She's willing to put up with a lot of abuse because it's preferable to her loneliness," she said.

Opening here on Sept 13, A Simple Favor charts the fallout of Emily's vanishing, which sets into motion a series of betrayals, secrets and revelations.

British-Malaysian actor Henry Golding, in his second movie role after portraying leading man Nick Young in Crazy Rich Asians, plays Emily's husband who ends up getting a little too close to Stephanie.

How did you find the humour in this dark story?

Stephanie is kind of pathetic and she lets herself be such a doormat, but I think it was important to find the humour in that, otherwise it could be really sad. I was worried Stephanie lets Emily and the mean mums at school abuse her.

Paul said, "I promise it's going to be funny, you're going to make it funny." So it was nice to be able to find those comedic moments and be dorky.

What was it like to work with Lively?

Blake is so sweet, open and warm, so it was amazing for me to witness her showing off her funny, dark side as Emily. I felt really lucky to have a good chemistry with her and be able to find the right tones for those scenes.

You are seeing this friendship grow, but there is also this undercurrent of toxicity and there is that kind of love-hate relationship. I was worried that you wouldn't believe that these two women were becoming friends.

We had to work hard to make sure it seemed like, even though the words we were saying to each other were loaded, there was a real warmth and love.

How was the kissing scene with her?

I always feel when I'm in a kissing scene with a guy, I have gum, I have mints, I'm flossing, because I'm so self-conscious. I think usually girls do that.

So Blake and I were having all these mints. It was the mintiest fresh kiss in the history of cinema (laughs). But neither of us wanted to be the aggressor in that scene. Blake worried that because I am in this vulnerable state and I'm crying, it would look like she was taking advantage.

I worried it would look like I take it too far, that she is just giving me a quick peck and I misinterpret the situation. It was interesting having a kiss with a female because it was a different dynamic from a guy, who just puts out his cigarette and is, "Okay let's go."

How was it like working with Golding?

Henry was so incredible. The funny thing was, we would be getting ready to do a scene and running the lines quickly before the camera was rolling and sometimes he would go, "I'm sorry, I forgot my line, I'm just really nervous."

It took me a second because I was, "Why is he nervous? Did something happen? Is he having some kind of personal family drama?"

I forgot it was his second movie, that he was inexperienced. That is a testament to his ability. It was really sweet the way he would get so nervous. But once we were on camera, you couldn't tell at all. And it doesn't hurt that he is incredibly good-looking.

Did he ask for advice?

You know what's funny? He didn't at the time. Then I saw him two nights ago and we hugged and the first thing he said to me was, "I would love to talk to you about how you do this." It was about the press and the promotion.

I was like "I know how intimidating it is and how you might feel like you're always about to say the wrong thing."

The first thing I told him was "If you are having a bad day and you're feeling stressed and overwhelmed, you have to forgive yourself for that. It is hard enough to feel all this pressure to be perfect and being tired and nervous. If you internally are having a bad day, you have to just let yourself feel that."

I hope it's going okay for him.

One funny scene in the movie sees you rummaging through Emily's closet and finding a dress you want. Have you ever done that in someone's house?

(Laughs.) I am totally that person who picks up all the lotion in the bathroom and smells it. Don't trust me to go to your house, it is bad. I have never tried on a dress before. Not yet, I am working my way up.

Anyone you desperately want to be friends with?

So many people. Right now, (Korean-Canadian actress) Sandra Oh. I just finished (her TV series) Killing Eve and I want to be her best friend so badly.

All the obvious ones too, Beyonce and Rihanna. But I think I might be too dorky to be friends with musicians, they seem so cool. Patricia Clarkson and Viola Davis - so many actress girl crushes.

Has anyone ever asked you for a simple favour that turned out to be different?

There are some movies I've done where it is, "It'll just be two days, we'll shoot out your part."

I don't love the script but I am friends with someone who is in it or the director. I will not name names, but it's, "Can you just come in for another week? Can we put your name on the poster?" I am like, "It's a two-day part, no, you can't." So I have to stop doing that.

The writer is the president of the Hollywood Foreign Press Association, a non-profit organisation of entertainment journalists that also organises the annual Golden Globe Awards.