It is notoriously cold—James Joyce immortalised the patch of Irish Sea as "scrotumtightening" in Ulysses—and Horgan wasn't a wild swimmer at the time, but she managed to brave a dip.

The creative jolt came, however, when she noticed a group of women somehow holding their weekly catch up in the breathtakingly cold water. "I thought, 'that's where the girls will feel safe enough to talk about their murder plans'."

Before you start suspecting Horgan of cold-blooded murder, she's talking about her fictional girls, the five Garvey sisters that take centre stage in her pitch-black comedy drama, Bad Sisters. She plays Eva, who became the surrogate mother to the other four after their parents died, including Becka (Eve Hewson), Bibi (Sarah Greene), Ursula (Eva Birthistle) and Grace (Anne-Marie Duff).

It's when Grace doesn't make it to their annual Christmas swim that they begin to break bad, rightly suspecting her emotionally abusive husband John Paul's (Claes Bang) hand in her ever-growing absence. Their nickname for John Paul is 'The Prick', although anyone who's seen the series will tell you that it sells him far too short.

It was Jay Hunt, Apple TV+'s Creative Director for Europe, who first approached her with the idea to adapt the original Flemish series Clan (2012). Horgan says that, beyond the "crazy premise," it was the abusive relationship at its core that most fascinated her. "I hadn't seen that kind of abuse on screen before, that coercive control, financial abuse and isolation."

"I hadn't seen that kind of abuse on screen before, that coercive control, financial abuse and isolation."

The fact that the abuse takes place in such a heightened comedy drama, though, made for a tough tonal tightrope to walk. For this, Horgan thanks Apple TV+ for giving them "free rein to make a show that is dealing with extremely sensitive material, but at the same time having four women chasing a man around Ireland, sometimes with no pants on, trying to kill him."

Horgan realised she pulled it off when, after the series aired, women who had experienced similar abuse started thanking her for making them feel seen. Although, she is quick to credit Duff and Bang's performances, which "felt like they really got under the skin of what it means to be in an abusive relationship."

While Bang "brought his own level of devilry" to John Paul as he shamelessly deceives, manipulates and gaslights his partner, Duff played Grace like a fading light; there are glimmers of the woman she once was, but for the most part they are drowned out by John Paul's brute force and her own cognitive dissonance. In one scene we see her literally shake her head free of the encroaching negative thoughts about her situation.

Another series of Horgan's also premiered in 2022: Shining Vale, a horror comedy starring Courteney Cox as a mother repenting for an affair by rebuilding her family in a new home—which just so happens to be haunted. It was therefore a year of departure for Horgan from the standard sitcom format she has arguably made her own, having won plaudits and awards for her comedies that have largely mined the various life stages of women: from 30s flat sharing in her debut Pulling (2006-2009), through to pregnancy and marriage in Catastrophe (2015-2019), motherhood in Motherland (2016-) and the self-explanatory Divorce (2016-2018).

She says the departure is deliberate, an attempt to avoid repeating herself and "to use muscles I haven't used before." But it's clear that she conceives of the genre almost like a Trojan horse: "[the series are] still dealing with subjects that I feel I can speak to, you know - women of a certain age dealing with the kinds of things you have to deal with... So what seems like a story about a woman trapped in a haunted house is actually a woman dealing with her own demons."

Likewise with Bad Sisters: it's full of thrills and spills given that the sisters make the most incompetent killers, mistakenly blinding a paintball instructor here, poisoning a dog with a laced liver there. But it's as much about Grace's abusive relationship and the other struggles the sisters face, such as Eva's with her infertility, or Ursula's unhappiness in her own, more mundane marriage.

You may have also spotted another of Horgan's favoured themes: family, and all the joys and pains that come with it. Perhaps unsurprisingly, Horgan grew up in a big one ("it's quite a thing in Ireland," she admits, "big families abound!") with the same number of siblings, five, as there are Garvey sisters.

"You can be really f***ing brutal to each other and get away with it because you know they're blood and they're not going anywhere"

She therefore "just knew" that putting five sisters on screen would make for dynamic viewing. "You immediately feel like you're part of a gang," she says, "and I'm not sure you'd feel the same kind of witch-iness from just a group of female friends."

The reason for the witch-iness, she explains, is that "[sisterhood] is closer than friendship because you've known each other all your lives, but you can also be really fucking brutal to each other and get away with it because you know they're blood and they're not going anywhere." We see this push and pull from the get go, as the Garveys' caustic banter kicks off just as they first come together to comfort Grace at the funeral of John Paul.

Writing such an atmosphere was one thing, acting it out with unfamiliar castmates was another. But Horgan says that all their hanging out, plus the nature and duration of the shoot, which lasted 10 months, naturally fostered the electric chemistry we see in the series. "You're essentially family at the end of that, I'm not joking. You're seeing each other from the crack of dawn, through night shoots, across birthdays... We were so tight by the end of it, it's just absolutely gorgeous."

It's currently awards season, and as we speak Horgan is waiting to board a flight to Los Angeles for a Vanity Fair promo shoot. But the joy she clearly took in the making of Bad Sisters makes you think that she'll pay the results little mind. Especially when she's already writing series two. "It's been an absolute joy to drop back into it. As soon as I get on the plane, my laptop's getting opened again."

And what's in store? "It's more of the sisters doing deeds out of love that just get them into terrible trouble. There are things from the first series that kind of come back to fuck with them... if you can find the right 'RTS way' of saying it."

Sharon Horgan was nominated for the Writer - Drama award for Bad Sisters at the RTS Programme Awards 2023.