No rehearsal? No problem. To deliver an authentic performance in Netflixs The Woman in Cabin 10, Keira Knightley did not rehearse any of her scenes. The decision not to walk through any of the sequences beforehand came from director Simon Stone, who emphasized spontaneity on set.

Keiras performance doesnt feel fake at all, Stone told Digital Trends about the lack of rehearsal. You go, Oh wow. Shes really reacting to stuff.'

Recommended Videos Based on Ruth Wares 2016 novel, The Woman in Cabin 10 follows Lo Blacklock (Knightley), an investigative journalist who finds herself covering the lives of the wealthy guests on a superyacht. One night, Lo witnesses a passenger being thrown overboard. Much to Los surprise, no one believes her. Something nefarious is going on below deck, and Lo must find out before its too late.

This interview has been edited for length andclarity.

Digital Trends: Anytime I watch a thriller with a mystery at the center, I feel like Im always trying to play detective and see if I can solve it before the big reveal. This movie is based on a novel. When you were first looking at the material, were you able to solve the mystery before it happened?

Simon Stone: No.

You couldnt piece anything together?

I think there are two different things. Theres a ticking clock in a film. I think in a book, you can put it down, and you can go, Well, I reckon these are the five options of whats happening here. In a film, the film keeps going. Even if your brain is going, Hang on, the other part of your brain is trying to keep up with the movie thats actually happening.

Related: This thrilling Netflix movie enlists Keira Knightley to investigate a horrible tragedy Thats the fun thing about the film. I think a lot of people have read the book who may or may not remember what the twist is. Even for those audience members [who read the book], its a fun thing to figure out how the heck we managed to pull it off, which is pretty miraculous in and of itself. But also, I think such a pretty significant audience for this wont [know the twist].

There is an overlap between people who read bestseller thrillers and people who watch Hitchcockian movies. I think there are significant parts of that Venn diagram that are free for people who have no experience with that book and are going to find it genuinely shocking. I still get questions from people who knew what the premise of the film was about and how we pulled it off. They genuinely cant figure it out.

In the notes I was reading, Keira said you didnt like a lot of rehearsal in this film. I find that interesting because of your background in theater, a medium that relies on rehearsal.

Well, I dont rehearse in the theater either.

Can you explain why?

In a film thats about people being surprised and shocked, you lose something, dont you? Everyone agrees with each other on how they do it. OK. Im going to walk through the door, and then youre going to be scared. I mean, that is a game my daughter likes playing with me. Im not sure how convincing I actually am when she walks through the door pretending to be a monster. The more you rehearse it, the more it loses a kind of fire to it.

Also, I love mistakes. Mistakes are like my favorite thing in art. For me, whenever I see a mistake, it feels like an extraordinary moment. If you try to repeat it, you cant. If you werent rolling when it happened, you just go, s***, we shouldve just shot that. And people say, Well, we should have shot it after rehearsal.

You dont have to do that anymore. Were filming on digital. You can literally shoot it. Why would you not press record, even if there are lights in the shot? Its because people want to protect themselves from making a mistake. If the focus is out or whatever, you dont want the director to be able to use that, so its a self-protective mechanism that people have. We dont want to rehearse the camera moves or know where the actor is going to stand.

But I keep walking in and pulling up marks that people had sneakily put down, and they conspiratorially agreed that the stand-ins would tell the actors where theyre supposed to stand so that they could get the focus right. I was like, No, I want to see someone straining to get the focus right. I want to see that buzz where, for a second, it goes out, then it comes in; thats all the subconscious stuff.

Now, it would be s*** if people were pretending to do a fake focus in a mockumentary or whatever. I find that annoying. What I find is that if you get the miracle of an extraordinarily well-shot film, and I think youll agree that its beautifully lit, it looks like a thriller. Its epic in scope.

There are shots that look tailor-made and rehearsed; theyre not. Even the shots of the boat in the fjord in Norway its me talking to the drone pilot while hes doing it, going, Yeah, go a bit to the left. Go down. OK, now do that. And talking to the boat captain, going, Could you speed up a bit? Could you slow down a bit? Can you turn to your left now?

Im talking to three different boats at once, and thats me just improvising. That requires a great level of responsiveness and a kind of spontaneity on the part of everyone, and really staying in the moment. What you get out of it, and Im sure youll agree, is that Keiras performance doesnt feel fake at all. You go, Oh wow. Shes really reacting to stuff. Thats a kind of strength that you get [when you dont rehearse], and I would sacrifice any track being slightly wonky or whatever for the beauty of that.

The Woman in Cabin 10 is now streaming on Netflix.