Casting directors like Mary Vernieu are rarely able to make as many discoveries at one time as the actors in Sam Levinson's HBO high school drama series.

One after the other, HBO’s incendiary new series “Euphoria” unveils acting discoveries. Exciting ones. Plus-size model and Instagram phenomenon Barbie Ferreira sizzles as zaftig Kat, who prefers controlling her virtual online sex partners to the vulnerability of building an intimate rapport with a real boy (Austin Abrams). “I don’t do virgins,” she tells him, not long after painfully losing her own maidenhead at a blowout party.

She is among several breakouts in this series created by showrunner Sam Levinson (the ex-addict scion of Hollywood royalty Barry), who wowed Sundance 2018 with hacking thriller “Assassination Nation,” which Neon picked up for $10 million (it grossed $2.5 million domestic). For “Euphoria,” Levinson hired again his “Assassination Nation” casting team of veteran Mary Vernieu (Bette Mae, Inc.) and Jessica Kelly (Chrystie Street Casting).

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Of course, their job is to give the showrunner options to choose from before HBO finally approves. But it’s unusual for casting directors to look away from established stars to find new faces and make discoveries. “It’s very rare to get a script or an entire series at HBO where they tell you they don’t need any names, just whoever is best to make this story,” said Kelly, who has teamed with Vernieu on multiple movies since Darren Aronofsky’s “The Wrestler.”

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“In this day and age the opportunity to discover people doesn’t happen that much anymore,” said Vernieu, who was an associate casting director for Billy Hopkins on Tony Scott’s “True Romance,” starring Christian Slater, Dennis Hopper, Christopher Walken, Patricia Arquette, Brad Pitt, and James Gandolfini. “You want someone who has some value. It’s a wonderful artistic process for us, to be allowed to dive in and find these characters.”

While the casting directors “had an idea of Sam’s taste and style going into ‘Euphoria,'” added Kelly, the pilot was “like nothing I had ever read or seen before. It is a bold, brave, exciting movie with a young cast. We have a great combination of some cast who have never acted before and someone like Jacob Elordi who came from Australia. It’s watching tons of tapes from all over the country, knowing what Sam likes, and bringing in different people and trying different things.”

HBO

First up was casting the series lead, an addicted teen who loves her family – who discover her overdosed and comatose in Episode 1 – but finds it hard to cope with the world without altering her consciousness. Zendaya’s casting was by no means in the bag: her management team wasn’t sure that playing an addict was the best thing for the 22-year-old rising star’s career. After all, the model and “Dancing with the Stars” contestant had already come into her own on Disney’s “Shake It Up” and “K.C. Undercover” as well as Hugh Jackman’s smash musical “The Greatest Showman” and Spiderman gal pal MJ for Marvel. But “Euphoria” offered her the opportunity to reveal her range, digging deeper in a way that no one was expecting.

Vernieu knew Zendaya could do it. And she argued vehemently to showrunner Levinson that the series needed the magnetic good-girl Zendaya to draw in the audience, giving them someone familiar to make them feel secure within a challenging contemporary milieu that often feels too authentic for comfort. “At first I thought she wouldn’t do it, it’s such a departure,” said Vernieu. “It was something so far from her persona. She’s got a lot of fans. Getting her people to take a minute to read it and pass it on: ‘Are you sure this is what you want to do?’ It’s a complex character. At the last minute she read it and wanted to do it. But she knew from beginning what to do with it, how important it was. She’s a smart girl.”

Zendaya took the role, with Disney’s “A Wrinkle in Time” star Storm Reid also extending her scope as her little sister. “Despite all the darkness and hardship, we have to have hope,” said Vernieu. “That’s what made Zendaya the perfect person to root for, so she could come through the other side.”

In order to cast a casting net wide across the country, HBO brought in another famous talent scout, Jennifer Venditti (“American Honey,” “Good Times”), who specializes in auditioning and finding unknowns who fit their roles perfectly, from Florida shopping malls to the streets of Ohio.

Vernieu is alert for certain signals when she reads a lot of people. “A perfect performance in the room is not what we are looking for,” she said. “We are looking for moments of brilliance, those flashes that show where it can go. Auditions are artificial, it’s really hard for the actors, hard for everybody—in a room, two chairs, not in the scene. What it’s really about when someone comes in? Is it an essence, is it organic? Do they feel like the character? You see the flashes, that one moment, ‘Oh my God!’ Once you send them off to do the movie or TV show, then they can go deep, access deep feelings, have layers, it can resonate. You’re looking for a person who has more to offer than what they’re showing.”

Eddy Chen/HBO

Venditti found model Hunter Schafer to play Jules, the new kid in town who has anonymous sex with the powerful parent (TV vet Eric Dane) of the big bully on campus (Elordi, star of Netflix’s “The Kissing Booth”), with whom she unfortunately falls in love. She finds real support from her loving best friend Rue (Zendaya).

Schafer was already a little famous: in 2016, the University of North Carolina School of the Arts grad and her father challenged a state House bill requiring that people use public bathrooms that match the gender on their birth certificates. To discover Schafer, Venditti searched LGBTQ centers, talked to people involved in the trans community, and found her via Instagram.

The casting directors narrowed the search down to three finalists who they brought in to audition. “Casting that one was extra scary, because these were not people trained at all as actors,” said Vernieu. “Hunter came in and won it in the room in a beautiful way. It was important that the character be very natural. Hunter had the experience – a lot of these kids are transitioning and going through this. She had never acted before. She could intuit what to do. Her performance is seamless.”

“She has so much heart,” said Kelly. “We get why Rue wants to stay clean for her.”

On “Euphoria,” Vernieu and Kelly were also watching interviews and tapes for how well actors were able to handle intense sexual material. “The main thing for Sam was to make them feel as comfortable as possible,” said Kelly. “There was an HBO intimacy coordinator to make sure every actor felt safe.”

Levinson wrote the role of Rue’s straight-arrow childhood friend Lexi for Maude Apatow after casting her in “Assassination Nation.” “It was always Maude,” said Kelly. “Sam fell in love with her, she’s so natural, she’s vulnerable and quiet. While writing ‘Euphoria’ she was always in his mind.” He cast Sydney Sweeney (one of the Manson girls in “Once Upon a Time in Hollywood”) as her sexpot sister Cassie, who is intoxicated by her ability to turn on men, but is terrified of losing her devoted boyfriend (“The Hate U Give” star Algee Smith), a gifted athlete who is pushed by his father to chase a football career.

Eddy Chen/HBO

Newcomer Angus Cloud, who grew up in Oakland 10 minutes from Zendaya, was Venditti’s other great find. He plays Fezco, the town drug dealer, who also doesn’t want Rue to self-destruct, and in one showdown, refuses to budge when she bangs and bangs on his door, desperate to buy drugs. Instead she is forced to call her AA sponsor (Colman Domingo), and starts to get sober.

Venditti found him in street casting. “He did not have to come in,” said Vernieu. “We saw the search tape –no question — he was the character, 100 percent, and even though he’s a drug dealer, he has so much heart. You can see who he is, he’s a natural. These kids, they’re young. They don’t have to be doing anything. They’re trying to figure out what they are doing.”

“There had to be a real connection,” said Kelly. “He feels like the real thing. That’s what’s so great about putting actors and real people together and making it all work.”

Everybody involved in “Euphoria” did something right: the series is connecting with younger audiences. “It’s HBO’s youngest-skewing drama series on the network’s digital platforms,” said HBO programming chief Casey Bloys at the TCAs, including HBO Now, HBO Go, and VOD options. “Euphoria” tops “The Deuce” and “Succession” in the 18-49 demographic and has seen a streaming surge. As the hub of WarnerMedia’s direct-to-consumer streaming service, HBO Max, which is scheduled to debut in spring 2020, HBO will need to pull audiences as they pivot from cable and satellite packages to streaming options.

Shows like “Euphoria,” with their young casts full of blazing talent, will lead the way.

Additional reporting by Ben Travers.

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