When Ambika Mod was first offered the role of Emma Morley in One Day, she turned it down.

As the 14-episode British series explores, sometimes impulsive decisions can send our lives off track, before fate intervenes to course-correct. Netflix’s adaptation of David Nicholls’ 2009 bestselling novel chronicles the slow-burning, two-decade-spanning relationship between Emma and Dexter Mayhew (played by Leo Woodall). 

Fortunately, it didn’t take 20 years for Mod’s destiny to become clear. “The change of heart happened very suddenly and without explanation,” the British actor (This Is Going to Hurt) tells Tudum, adding that her initial hesitation stemmed from a genuine love for the source material, having read the book when she was 13. “I just didn’t see myself in that role, to be honest. It took well into the shoot for me to convince myself that it was the right call for me to be there doing that.”

Nick Thompson for Netflix

For Woodall, who was drawn to Dexter’s silliness and vulnerability, saying yes to the part was instantaneous and followed by “a huge sigh of relief.” After going through what he describes as a “rigorous audition process” (including multiple rounds and read-throughs of some of Dexter’s heavier scenes), the White Lotus actor was eager to dig into the role. “It’s just a beautiful, beautiful story, and it has this legacy already,” he tells Tudum about the novel, which was also adapted into a 2011 film starring Anne Hathaway and Jim Sturgess. “Both characters are so well-formed. There’s a huge [amount] of joyfulness.” 

For Mod, part of the project’s joy came from working with Woodall. “I was waiting for a while to find out who my Dexter would be, and was very happy when it was Leo,” she says. The pair met up after being cast for “a coffee that obviously then turned into a gin and tonic instead,” says Woodall.

After Mod and Woodall were cast, lead director and associate producer Molly Manners (who helmed Episodes 1, 2, 3, and 14) didn’t want the duo to rehearse their scenes too much. Instead, she would have conversations with the actors while they were in character to get them used to being in Dexter and Emma’s headspace. “I want to be rehearsing with improvisation, basically, and playing around the topics, and the areas, and the different years,” she says. 

On screen, Emma and Dex meet for the first time on July 15, 1988, the night of their graduation from the University of Edinburgh. After an unexpected hookup, the wide-eyed graduates share their dreams. Emma, an aspiring writer, tells Dexter she hopes to one day change her tiny corner of the world. Dexter, on the other hand, is shooting big for fame and fortune. The next morning the conversation continues as they hike the Scottish capital’s ancient volcano, Arthur’s Seat. (The cast and crew actually did hike to the landmark peak to shoot those scenes. “I climb Arthur’s Seat every time I do an Edinburgh Fringe, so I’ve done it about four or five times, but it was very surreal filming up there,” says Mod.)

Ludovic Robert/Netflix

Back on flat ground, Dex and Em — as they call each other — go their separate ways, but promise to stay in touch. Each episode revisits the duo one year later on this one particular date, as the circumstances in their lives push them together and pull them apart. 

Initially, unlike a disillusioned Em, who’s serving terrible Mexican food at a kitschy restaurant two years after she graduates, Dex’s star is rising quickly. His good looks and charm land him in front of the camera, presenting a late-night show. In Episode 3, he visits his best friend in London, where he and Emma hike Primrose Hill and linger on the hillside, catching up as the sun sets. 

In the scene, Em says she plans to move back to her hometown of Leeds, confessing that she’s feeling at a loss after the failure of her first foray at playwriting. “Did you write something else? Did you keep going? No. You buried yourself in quesadillas,” Dex bluntly tells her. He’s the only person who can push Emma to realize that being an idealist won’t automatically make her dreams come true — and, in turn, she’s the only one who can quickly humble hotshot Dex. 

Nick Thompson for Netflix

Em’s early years struck a chord with Mod, who started out in standup. “That was definitely me when I graduated from uni: full-time jobs and gigging in the evenings and doing comedy,” she tells Tudum. “I definitely related to the frustration she felt with that.”

That crisis-of-confidence Primrose scene, the first long conversation Dex and Em have in Emma’s bedroom in Episode 1, and the maze scene in Episode 10 were the three scenes Mod and Woodall performed during their chemistry read. “They were all, like, 10 pages long and we did them all several times,” says Mod. “So it was very, very rigorous.” Manners, who was present during the chemistry reads, adds, “They just felt like they knew each other and they were at ease with each other.”

As the episodes progress, Em eventually finds a career in teaching that gives her purpose. “I suppose the confidence that she gets from teaching and from that career path is something that I felt when I started acting,” says Mod. But as the years pass and Dex struggles to come to terms with his mother’s death, he starts relying on alcohol to help him through the day and finds himself wandering down a dark path. “The thing that really drew me to him was the painful moments,” says Woodall. “I felt like I just really wanted to — it sounds weird saying it — help him out.”

Ludovic Robert/Netflix

The story continues into Dex and Em’s 30s — years both Mod and Woodall, at 29 and 27, respectively, haven’t experienced. “We played so many years of Emma and Dexter's life that we haven’t lived yet [since] we’re obviously much younger than Emma and Dexter are in the last half of the series,” says Mod. “It was weird.” They also had to familiarize themselves with ’80s and ’90s phones and computers that they weren’t alive to see in action. “We had to get taught how to use a lot of old tech,” says Mod. “We were like, ‘What’s this?!’ ”

With the sweeping highs of One Day’s will they, won’t they romance come the crushing lows that are hard to shake off for viewers and actors alike. So when Dex and Em finally find equilibrium in their relationship after so many years, it feels cruel when their love story comes to an abrupt end. “It’s so unbelievably heartbreaking — you feel a bit robbed,” says Woodall. “I found it quite hard to snap out of it after we finished.”

In the final episode, Dex sits alone in the bedroom that he once shared with Em. Surrounded by moving boxes and with only a bottle of liquor for company, his grief is overwhelming — until he imagines and speaks to a vision of Emma. “It won’t always be like this,” she reminds him. “You’ll feel guilty and hungover and just shit. All day. And it’ll go on like that, until it doesn’t. ’Cause one day, it won’t.”

Nick Thompson for Netflix

Mod says Episode 14 was actually among the first ones they filmed during production. “That was quite a special day,” she shares. “Someone yelled ‘Cut!’ — and it was just silent. I walked out of the box room and Molly, our director, came up to us and she was just in tears, and everyone else was on the brink, and I was like, ‘Oh, maybe we’re onto something quite special here.’ It was very validating and reassuring to have that reaction.”

For Woodall, it was an “intense” scene to shoot. “It would start with just me in the room and Andrew, our camera A operator who we both loved so dearly, and I felt instantly safe,” he says. “And then very quietly, Ambika would come into the room and just sit down and we’d carry on with the scene. It was very beautifully done.” During filming, Woodall would wipe his tears each time he cried, but Manners didn’t want him to hold back.  “I was like, ‘This time don’t wipe them away. I know it might feel gross but let's try it. Just let them fall,’ ” the director adds. “And I just find it so beautiful and kind of cleansing when you see that.”

By series’ end, we’re left knowing that with time, Dex will — one day —see the clouds part. “It could have been easy to end it in a way that was just like, ‘Well, that was the saddest thing I’ve ever seen,’ ” says Woodall. “But they don’t. They leave it very hopeful.” That’s reinforced by One Day’s final sequence, a montage of Dex and Em kissing throughout the years, starting with their lip lock after hiking Arthur’s Seat. “It’s a very wholesome way to leave them,” says Woodall.

Mod thinks it was “only fair” to say goodbye to Em and Dex in that way. “I think that’s what’s heartbreaking about the book — it’s this juxtaposition of these two wide-eyed students and the dreams they have for their future, and then how things actually turn out.” But until they saw the final cut of the last episode, the two leads didn’t know that the montage had been added.  In fact, it wasn’t included in the script. “It was really this thing of flicking through a photo album and just all those memories, like flashes and moments, [coming] to you,” says Manners, who came up with the idea with director of photography Nick Cooke. “That was new for us,” says Mod. “It so encapsulates what that moment is trying to do and what the book does so well. It’s very hopeful and beautiful. It really took my breath away.” 

One Day is now streaming on Netflix. 

One Day Trailer