See Yara Shahidi and Odessa A'zion in Emotional Trailer for 'Sitting in Bars with Cake' (Exclusive)

"Sitting in Bars with Cake," starring Yara Shahidi, Odessa A'zion and Bette Midler, premieres Sept. 8 on Prime Video

Sitting in Bars with Cake is pushing a close friendship to the emotional extremes.

PEOPLE has the first trailer for the film from director Trish Sie (Step Up: All In, Pitch Perfect 3), written by Audrey Shulman and based on her 2015 book of the same name.

Sitting in Bars with Cake, inspired by true events, follows lifelong pals Jane (Yara Shahidi) and Corinne (Odessa A’zion) navigating their 20s in Los Angeles until a medical diagnosis changes thing forever.

"Corinne, the ultimate extrovert, convinces her shy but extremely talented home-baker best friend Jane to commit to a year of baking cakes and bringing them to bars, with the goal of meeting people and developing confidence," a synopsis reads.

"During their year of 'cakebarring,' Corinne receives a life-altering diagnosis, and the pair face a challenge unlike anything they’ve experienced before."

Sie spoke with PEOPLE about what inspired the film, and working with Shulman, "the protagonist in real life" who lived a story similar to Jane's.

"[Audrey's] best friend through this whole thing — who kind of masterminded and believed in this whole project — also had this incredible diagnosis in the middle," says the director, 51. "She insisted that they keep going, and Audrey herself had to step up and really become a whole different version of herself essentially."

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Sie says the real-life close friendship between Shahidi, 23, and A'zion, 23, was "a wonderful bonus" when casting, in that "they already had this kind of shorthand and easy affection for each other and trust of each other."

"Yara was my dream Jane from the beginning because I've known her since she was quite young," she says, noting Shahidi's "thoughtful, profound" nature that she has had since childhood. "Then we had to set about finding the right Corinne to match her."

In A'zion, Sie found something "that was just so specifically spirited and so effervescent and kind of unpredictable, but in this really exhilarating way."

Bette Midler also appears in Sitting in Bars with Cake as Corinne's boss. As a big fan of Midler's, Sie admits she "was shaking in my boots because I love her so much and I was so excited and nervous and scared" to meet her.

But she had nothing to fear, as she says Midler, 77, "is actually so incredibly lovely," and just "as funny and edgy and creative as you would say she is."

Midler also had no desire to play out any kind of "boss lady" stereotypes and instead took the depth and "mothering instinct" of her role to heart.

"I love that she brought this sort of warmth and dimension to a character that could have been a little bit of a cardboard cutout. That's just not how she does things," Sie says.

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The cookbook that Sitting in Bars with Cake is based off on, Sie says, includes "sweet, happy" stories of people from all walks of life. The film adds something in the form of "a message about not just surviving through a tough time, but thriving through really challenging times in our lives."

While young-adult women are the "obvious" target audience, she also thinks men, older people and many more "will love it" for its universal themes and "fabulous performances."

"It's a story of what happens when the map that you think you're following in life kind of goes offline and you have to figure things out without anything to guide you besides your own internal compass," Sie says.

She adds, "It's about figuring out life when it throws you a pretty wicked curveball, because that is one thing that we all have in common."

Sitting in Bars with Cake is streaming Sept. 8 on Prime Video.

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Read the original article on People.