Inside the making of Netflix's poignant, beautiful One Day adaptation

Warning: This post contains spoilers from Netflix's One Day.

Dexter Mayhew isn't the only one who fell in love with Emma Morley.

"I was obsessed with Emma back in the day," says Nicole Taylor, the creator of Netflix's One Day adaptation. "Every young British woman related to that girl. She's just one of the most well drawn female characters in fiction." That's why Taylor couldn't say no when presented with the opportunity to tell Emma's (and Dexter's) story on the small screen.

In 2009, David Nicholls released his novel One Day, which followed the incredibly charming Dexter and the incredibly smart Emma as they met at university and embarked on a 20-year friendship (filled with sometimes-spoken romantic feelings). The story itself wasn't inherently unique, but the way Nicholls chose to tell it was: As its title implies, the book checked in on its characters for one day each year.

As Nicholls previously told EW, "The premise of the novel was it should be like looking through a photograph album in the way that a photograph snatches a moment in time, that these days are little vignettes of how you were at that time."

In 2011, Nicholls himself wrote the screenplay for the story's big-screen adaptation, which starred Anne Hathaway and Jim Sturgess. But when the idea was brought to him for a TV show, something clicked. "The mathematics of doing a movie that covers 20 years, it gives you six minutes a year at most. And one of the central things to the conceit of the novel is that some days are more eventful than others. And in a movie, those are the days that you're going to have to tell in two minutes," Nicholls says. "In a TV show, they can become something else."

With more time on their hands, the question then became how to best tell Dex and Em's story. "I wanted to be as faithful to the book as possible, and I wanted to snapshot this day every year, whether they're together or they're not," Taylor says. " The question was the same: Where are they at in relation to each other, even if they're not in the same frame, even if they're not in the same episode? That is the overarching question for the series. I felt that was very truthful to those kinds of relationships."

"This is what's so universal about the book. I think that is an experience that so many people have," Taylor continues. "It's usually with someone you have virtually nothing in common with superficially, but there's something in you that they, on a soul level, recognize, and vice versa."

Taylor ultimately decided she wanted to "observe that relationship through time" and not worry about things like flashbacks. "They're brilliant characters, let's just be with them over time," she says. But how much time? Netflix allowed Taylor to determine the episode count for the series, and although Taylor admits that the original plan was 20 episodes for 20 years, ultimately, they felt the story was best served with 14 episodes that followed Dex and Emma as they graduated from university, suffered through terrible jobs and failed relationships and just generally learned how to exist with (and without) each other. But the story doesn't work without Emma and Dexter ... which brings us to casting.

Ambika Mod and Leo Woodall both remember meeting at the chemistry read. There were three Dexters and three Emmas, and by the end of that day, there'd only be one of each. "You were the second Dexter that I read with," Mod says to Woodall, to which he responds, "I think you were the second for me, too."

Both actors had a difficult task in front of them. For Mod, it was about bringing to life a character that felt so relatable to so many women (and, in particular, Taylor). "I'd read the book when I was really young and I knew how beloved Emma was and how basically everyone who reads the book sees themselves in her," Mod says. "She is, I think, the grounding character in so much of the novel. So yeah, I felt pressure. It also took me a while to see myself in the role because I didn't foresee me ever being able to play a character like this. She's written as white, she was played by the beautiful Anne Hathaway. I just didn't see it matching up. But when I re-read the book when I was auditioning, we just have so much in common and she's so British and she's so funny and she's so dry. I just fell in love with her all over again."

Although Mod recalls the hard work that went into the audition, like spending "ages" perfecting a Yorkshire accent, for Taylor, the decision was obvious. "It was a dream situation," Taylor ays. "Ambika walked into the room and it was just instant. There's my dream for Emma. There's nothing archetypal about her. She was complex, peculiar, she seemed quite withdrawn, kind of nervously ironic. It reminded me of being that person in the '90s."

Woodall's challenge was a bit different. It's not so much that Dexter is beloved — he is — but that over the course of 20 years, he goes through some phases that can feel frustrating. It's not always easy to root for him. "One of the things that I was wondering before I went back to the book was, who's going to put up with this dick?" Taylor says with a laugh. "Times have changed."

Although Taylor recalls many actors doing their best Hugh Grant impressions in the auditioning room, Woodall took a different approach. "He brings this innate vulnerability to the character, and you can feel that vulnerability quite early on," Taylor says. "Yes, he's one of those guys we all went to college with who feels that he's going to inherit the earth. But he's just so bloody appealing, and you can see the wee boy in him from the very beginning that I think you're rooting for him always. And that's Leo. He's just divine."

Woodall was careful not to judge his own character. "I definitely wanted to maintain the goodness about him throughout if I could," Woodall says. "There are times where that was pretty difficult. But I think there is a lot of good in him, and I think it is important for that to be prominent."

But Woodall had no idea what he was in for. Although the series largely shot chronologically, less than a week into production, they filmed episode 14. "It was day four that we did the first year after that moment," Woodall says.

We'll say it again — spoiler alert!

But "that moment" refers to something book fans have been dreading: Emma's death. It was something Taylor admits she "interrogated fully" in terms of whether they had to include the devastating twist in the show. "I didn't feel any pressure to change the ending or to keep the ending," Taylor admits. "I just wanted to reinterview it for its place in the piece."

In the end, she felt it was necessary to the "structural and thematic integrity" of the piece. "Once you pull that out, you better have something just as good, if not better, in terms of the meaning of the piece as a whole and the cosmic enduring nature of love and friendship and how your whole life can be defined by a chance."

And so, just like it happens in the book, Emma is hit by a car while riding her bike, and her story comes to an end in episode 13. "I was nervous because that is such an iconic moment in the book," Mod says. "So many people who read the book say they remember where they were when Emma dies, and the way that David wrote it is so abrupt and heartbreaking. And so I was nervous for that scene."

Not only was the scene practically difficult — Mod recalls freezing temperatures, fake rain, and lying in a contorted position for a long period of time — but she wanted to get the emotions right. "I focused on her thought processes. There's a whole thing in the book about her noticing people's feet and thinking, 'People are looking at me,' but then she can't move and then she thinks about a flashback to her childhood and then everything just stops. I really focused on that thought process and hopefully that conveyed."

All of that occurs in the penultimate episode, which Nicholls himself wrote, meaning Woodall filmed the heaviest part of the story during his first week as the deliciously bubbly Dexter Mayhew. "It was horrible, I'm not going to lie," Woodall says. "But in a way, it was nice to get some of it done early. I think if it had all been at the end, it would've maybe been looming on my brain the whole time."

If nothing else, filming life after Emma early on meant Woodall got to spend the rest of the shoot in the days that made their love story unforgettable. And together, he and Mod have given new life to a story fans first fell in love with 15 years ago, fans like Taylor.

"My baby was like five days old when I got a message from a producer saying, 'Do you want to do it?' My very firm plan had been don't do any work for a year," Taylor remembers of the moment she was presented with the opportunity to make the show. "But I'd read the book back in the day, so I thought, I better just check, I'm sure it won't have stood the test of time. Then I re-read the book, stayed up all night reading, loved it. I couldn't not take this job."

Much like in Dex and Em's story, that one choice changed everything.

One Day is available on Netflix now.

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• Book review: One Day