‘Certain themes really choose writers,” says author Coco Mellors from her home in New York, where she lives with her husband and son. “Addiction is a theme I never really chose to write about, but I cannot escape it.”

Mellors’ bestselling debut novel, Cleopatra and Frankenstein, is about a whirlwind romance between struggling artist Cleo and functioning alcoholic Frank. Published in 2022, the book has sold nearly 200,000 copies in the UK, catapulting Mellors from obscurity to literary stardom. It became an “It book” on social media, largely thanks to its artfully designed cover (a crudely rendered oil painting of a sad, beautiful woman by Gill Button, designed by Jo Thomson), and was chosen as Carrie Bradshaw’s bedtime read in an episode of And Just Like That. TV rights were sold to Warner Bros in late 2022, with Mellors signed on to adapt it herself.

Alcoholism and addiction play equally, if not more significant roles in Mellors’ highly anticipated follow-up novel, Blue Sisters, about three sisters who have recently lost the fourth sister in a tragic accident. Set in Paris, LA, London and New York, each sister wrestles with her own ruinous habit – a legacy passed down from their alcohol-dependent father.

“I’ve been sober for eight years and I come from a family of addicts and alcoholics, almost all of whom are sober as well, so I was interested in writing about addiction in families,” Mellors says. “I’m also interested in sobriety in families and how that can get passed down through generations. What does it look like to be long-term sober but still self-destructive? What does it look like to be newly sober and starting to heal? What does it look like to have never drunk or done drugs, but still have the impulse to escape yourself, which I think Bonnie has,” says Mellors of the second-eldest Blue Sister, a champion boxer with a penchant for pain.

Mellors is the youngest of four herself; she has two half-siblings, Holly and George, and a sister called Daisy, whom she describes as the love of her life. While the Blue Sisters are not based on her own family – “they arrived like babies in a box on my doorstep, they were fully formed characters” – she was inspired by the formative nature of sibling relationships. “In therapy, all roads lead back to the parents. But I started to have this feeling later in my life, that a huge reason that I am the way I am is because of [my] siblings,” she says.

Despite the obvious parallels, Little Women was not Mellors’ “north star” when writing the novel. “One of the things that struck me first was [Wes Anderson’s film] The Royal Tenenbaums, this feeling of different, very exceptional siblings within one family.” She was also inspired by the way Jonathan Franzen writes siblings in his novels.

The author speaks about her literary influences like a dreamy-eyed school girl. During our hour-long conversation, she quotes a number of her heroes: fashion journalist Diana Vreeland (“The best thing about London is Paris”); writer Henry de Montherlant (“Happiness writes in white ink on a white page”) and boxer Anthony Joshua (“Don’t let success get to your head or failure get to your heart”). She has a tendency to speak in aphorisms of her own making, too: “New York is hard on the body and LA is hard on the soul,” she tells me at one point.

Mellors was born in north-west London and moved to New York with her family as a teenager (her British accent is still very much intact). She took a master’s in creative writing at NYU, where Martin Amis and Amy Hempel were among her tutors. She then moved to LA, where she lived for three years and worked as a copywriter to pay the bills until Blue Sisters was sold. During her time in LA, she miscarried, which ultimately shaped the novel’s ending. “That loss, it taught me something new about grief and the way that it permeates everything,” says Mellors. “I had initially written an ending which was less hopeful […] But I realised that I needed from the book something that I needed in my life, which was a sense of hope.”

Screen rights for Blue Sisters are out on submission. In the meantime, Mellors is working on her third novel, about a young woman in Paris during the city’s hottest summer ever, whose personal life is also “coming to a boil”.

“She’s [deciding] whether to stay in Paris and pursue her career as a film-maker, or go back home to America by the next time she ovulates to try to have a child,” says Mellors. “It’s the internal clock of her body, which is pushing her home, versus her desire to pursue the life of an artist.”

It will be the first book Mellors has worked on as a full-time novelist, though she admits to being distracted. Her son, Indigo, was born two months premature in 2023, soon after which Mellors and her family returned to New York. “It feels like this mad love affair that I’m dying to start, but I can’t,” she says. “But the novel is always running beneath the surface for me.”

• Blue Sisters will be published on 23 May (Fourth Estate £16.99). To support the Guardian and the Observer buy your copy from guardianbookshop.com. Delivery charges may apply.

• In the UK, Action on Addiction is available on 0300 330 0659. In the US, call or text SAMHSA’s National Helpline at 988. In Australia, the National Alcohol and Other Drug Hotline is at 1800 250 015; families and friends can seek help at Family Drug Support Australia at 1300 368 186