In the folklore that has grown up around the Coen brothers over the past 40 years, there are two siblings, Ethan and Joel, and Joel’s wife, actor Frances McDormand, who has been a regular since their first film, Blood Simple, and bagged an Oscar for her unforgettable performance as the pregnant policewoman in Fargo. Ultra-swotty groupies may remember that Ethan’s son, Buster, was credited as Matt Damon’s abs double on True Grit, though Buster was barely into his teens and Damon never displayed his abs.

But unbeknown to most, on seven of the Coens’ films, up until 2001’s The Man Who Wasn’t There, a fourth member of the clan was working away behind the scenes. Tricia Cooke joined the team as an assistant editor on Miller’s Crossing, which was filmed in New Orleans, rising to become their regular film editor. “At the time, I really didn’t know who Joel and Ethan were. I hadn’t seen Blood Simple or Raising Arizona, but I really wanted to go to New Orleans,” says Cooke. She and Ethan quickly hit it off, but there was just one problem: “He asked me out on a date, and I told him I was a lesbian.”

For a time they remained good friends. “We would hang out. We did a lot of reading together. And then years later I was like: ‘This is silly. I kind of love this man.’” So they married, had two children “and made the relationship work”. They both have other partners and live in different parts of the same house in New York, but they all get together in the kitchen.

Though they have never been secretive about their family setup, it has taken a film to introduce it to the wider public. Drive-Away Dolls, written by the couple, is a lesbian road movie crossed with a crime caper, set in the 1990s, with a trippy cameo for Miley Cyrus in kaleidoscopic 60s flashbacks depicting the adventures of Cynthia Plaster Caster (a real-life artist and “recovering groupie” who specialised in casting celebrity penises).

The film is a glorious whoop for personal and sexual freedom that raises two fingers at the sort of repressive social values that, particularly in this election year, can be found blaring from billboards along the highways of the Republican American south. Matt Damon plays a hypocritical senator. “We looked at a lot of Ron DeSantis and Marco Rubio photographs when coming up with his look,” says Cooke. “And that was very present in our minds… how can we thumb our nose at all of those Florida politicians?”

Coen and Cooke are sitting side by side in their New York home when we meet over Zoom. While he fiddles with a pen and holds himself at a slightly uncomfortable angle to the screen, she sits warmly forward as if looking to form a two-way relationship with the room behind me (later on, it turns out that she actually is: she has spotted a jigsaw on a table and wants to know what the picture is).

The couple have a bantering rapport that frequently erupts into laughter, starting with the very first question: how did the film come about?

“It’s like the beginning of a joke. It started with Trish sitting in a bar,” says Coen.

“Lesbian sits in a bar,” quips Cooke.

“Tell me if you’ve heard this one before,” riffs Coen.

Cooke picks up the thread, explaining that she was in the bar with a close friend discussing their experience of road trips, including one she had made as a student, travelling across the country in a rental – or drive-away – car. “And we just thought that sounds like a fun movie, so we came up with the title, Drive-Away Dykes. And then I came home and mentioned the title to Ethan. And we thought: ‘Yeah, that’s a great title. Let’s write that movie.’”

Actually, says Coen, “Trish is understating it a little. She came home and said three words: Drive-Away Dykes. And I was thunderstruck. Like, I couldn’t talk. I had to lie down and put a cold compress on my forehead. I was so taken with the title. I said, ‘OK. Yeah, right, let’s make that movie.’”

By the middle of the 00s they had written a script and suggested it to their friend Allison Anders, who had made her own successful road movie, Gas Food Lodging (1992). But, says Coen, the idea of a fun lesbian movie “flummoxed people. It just didn’t compute. Or at any rate, we didn’t succeed in convincing anyone that it made sense.” So they consigned it to a drawer and got on with their lives.

“I think,” adds Cooke, “that maybe the flippancy of it, or you know, the irreverence was just not the flavour of the month at that time. We knew that it wasn’t just going to be a fun road movie. We wanted to have some kind of mystery, and we wanted there to be two couples, so it juxtaposed a female couple who are engaging and have their shit together with some bumbling men who are inept.”

The engaging women, Jamie and Marion, are charismatically played by Margaret Qualley and Geraldine Viswanathan. The film opens with Jamie’s police officer partner coming home to find her engaged in enthusiastic sex with another woman in their apartment. Booted out of the house, Jamie invites herself along on her more uptight friend Marian’s road trip from Philadelphia to Florida, demanding that they stop off at all the lesbian bars along the way. What the pair don’t realise, until they suffer a puncture hundreds of miles into their journey, is that their rental car is carrying a couple of mystery boxes in the spare tyre compartment. “Don’t open the box!” squeals Jamie when she spots them. “I saw this movie and it was really, really bad…”

It’s one of many classic Coen moments of intertextual japery. And of course the bumbling duo are already hot on their heels, creating a running gag as Joey Slotnick and CJ Wilson – two character actors who have collaborated with Coen in one of his other lives as a playwright – trail their quarry through a series of hookups, one of which involves a whole team of lusty female footballers.

The setup gives a big wink to the exploitation movies of the 1960s and 70s. “It’s kind of implicit in the title. It’s a trash title for a trash movie. I mean, people like – we like – trash movies,” says Coen. The only alteration demanded along the way by their production company was to change “dykes” to “dolls”. “In their defence, they were tickled by the title,” says Coen. “But you know, a reality began to emerge that the theatre chains just wouldn’t book a movie with that title. It was a practical impossibility.”

Cooke leaps in with a qualification of the word “trash”, explaining: “It’s trashy in the sense of being promiscuous, which isn’t necessarily trashy, but women are not often allowed to be promiscuous in life, you know, and especially, I had never really seen it in lesbian films.” She concedes that there was a promiscuous character, Shane, in the lesbian comedy series The L Word around the time they were writing the script, “but it’s just not a character type that you get to see a lot. We wanted there to be fun, playful sex in it. We thought, ‘OK, we’re going to make this raunchy movie, not in a dirty way, but in a way that makes the point that women have libidos too. And that’s great. Let’s celebrate it.’”

The lesbian bars in the film are in part a homage to those that Cooke used to frequent in New York and elsewhere, most of which no longer exist. Of her unconventional domestic arrangement today she says: “It’s very easy for us, you know. We just like each other a lot. So we really enjoy working together, collaborating, coming up with ideas together.” Yes, adds Coen: “I would think it’s boring to hear we just like each other, we love each other, we get along.”

Cooke, who is now 58, stopped working on Coen brothers films in the early 00s when their children were small, but went on doing other editing work and has a second life as a political activist for “queer rights, trans rights, just trying to get Trump impeached, and things like that”. She helps to organise the annual Queer Liberation March in New York, and works with the direct action group Gays Against Guns. “Our country is so divided right now. And there’s no compromise. So it’s very hard for the two parties to come together to make a healthy working government,” she says. “Also it’s important for women to have bodily autonomy – to be able to make choices in their lives. And so many people in this country want to take those rights away.”

After so long in the background, what is it like for her personal life to be so scrutinised? “Well, being in the public eye is new, and people want to know all this stuff, so it’s been a little odd,” she says. “But I’ve always been openly lesbian. I came out when I was 21. So people in my family and my friends know, but not in a public way. My mother passed away recently. And, you know, I’m sure she’s happy, somewhere out there, that she doesn’t have to experience this. But a lot of what I do in my private time is trying to destigmatise queer life, so I’m happy to talk about it if someone’s interested in reading it. If it helps someone, then great.”

Cooke’s activism has led to several arrests. “Ten of us shut down the Capitol rotunda on the day of the final hearing in the Senate for Trump’s impeachment,” she throws in. “We sat down in the middle and we chanted. That was rough. They chained us to the wall. It was fun, but definitely the most intense.” The usual outcome, she adds, is “they come and physically take you down into the basement, then it’s a wagon. And someone comes and pays your bail. Though usually you know how much money you’re going to need so you take it with you – along with a warm sweatshirt, because you know it’s going to be cold in jail.”

Coen, who is 66, doesn’t participate, and wasn’t in town on that occasion. “But I did have a picture of Trish being led away in handcuffs,” he says. “I sent it to a conservative friend of ours with the message ‘My wife. I think I’ll keep her.’”

When I suggest that Drive-Away Dolls carries a strong political message, Coen goes evasively runic: “Strong? It is and it isn’t. It’s a movie kind of with nothing on its mind, but also with everything on its mind. OK. And I won’t disavow it. You can have nothing and everything on your mind.”

In general, he admits, he is the warier of the two about putting himself on the line politically. “I’m definitely the reactionary in our very small universe. I feel immediate discomfort talking about this stuff as frankly as Trish does. Partly – but not wholly – because, in a way that’s connected to this movie, it’s good to leave things unsaid. Here’s what this movie leaves unsaid: there’s a love story, a romantic comedy between two women, and all the political explicitness and commentary is left unsaid, and you go: ‘OK. Does anyone have a problem with that?’ It’s just taken as a given. The political statement is left tacit. And I like the tacit.”

Shortly before the pandemic, Coen was reported as saying he was going to stop making films with his brother because it had all become too stressful. “It’s a little inaccurate to say I stopped working with Joel when in fact I just stopped working because I couldn’t be bothered. The last couple of movies we did were difficult. They were trying production experiences because they were so scattered and big,” he says. The Ballad of Buster Scruggs involved “six different westerns, six different casts every week. It was like we were making a new movie, frequently in a new geographic place.” The weather was a headache, “and as for the horses… don’t even get me started”.

Hail, Caesar!, which preceded it, was similarly challenging: “Every week we’re starting a new different set piece. It’s not that it wasn’t fun on certain days – it was always kind of fun, but less fun than it had been.” When the brothers talked it through they realised that the last time they had both fully enjoyed going to work every day was on 2013’s Inside Llewyn Davis. “So you know, after those two movies I thought, OK, I need a break, which I took, and then – predictably maybe – got bored.”

His response to boredom was to write a collection of five one-act plays, A Play is a Poem, which premiered at Los Angeles’s Mark Taper Forum in 2019 and was about to transfer to New York when the pandemic struck. He whiled away the dark months making a smart cut-and-paste documentary about Jerry Lee Lewis, which Cooke edited. Then they went back to the script in their bottom drawer. Though for technical reasons Coen is credited as the director, he is careful to emphasise that they in fact made every part of it together – as he and Joel do on their films. “It’s very equal. We at every stage talk the movie back and forth, in terms of the writing, and then on the set, and then cutting. It’s all just making the movie.”

Both are wistful about the long-ago days of B-movies, with names like Kiss Me Deadly, when the stakes were lower while creating the onscreen illusion that they were sky high. “I feel like the recklessness that existed back then gives those movies energy, and we were trying to duplicate that kind of carefree effect, a little sloppy, a little messy. We did it as much as we could,” says Cooke.

“Given our own uptightness,” butts in Coen, “you know we hit our limits. I was, like, are you crazy?”

“Well,” replies Cooke. “I’d never made a movie on this scale before. So I was very naive. For me, everything was like, ‘Oh, don’t worry, it’s going to happen.’ I didn’t have as much anxiety as either Ethan or our producer. So I’m going to say that Ethan is the more uptight one.”

* * *

Coen and Cooke have the script for another “lesbian B-movie” ready for production: it’s called Honey Don’t, and will again star Qualley, this time as femme fatale private detective Honey O’Donoghue. Cooke, meanwhile has a couple of other collaborations on the go, including an adaptation she’s working on with their 24-year-old daughter, Dusty (their son, Buster, now 28, banked his abs credit on True Grit, which was a joke of his own suggestion, and is now working as a history and English teacher).

“It was never an ambition of mine to be a writer or a director,” says Cooke. “My ambition was to be a film editor.” She can’t imagine directing solo. “It would just be such a huge responsibility. But I’d like to write and I love to collaborate. So if I find good partners to collaborate with, then yes, I mean, I’m happy to do all of those things. But this has just been a really lovely, pleasant surprise: so OK, I’m here now, and I’m going to work as hard as I can. Then, you know, maybe I’ll go and garden after this. I don’t really know.”

“Ethan,” she adds, “just loves to write.” He’s the author of two poetry collections and one of short stories, as well as the plays. The Coen brothers partnership is also cranking up again. “A few months ago we wrote something that hopefully we will do,” he says. Do they work in person or remotely? It’s getting harder always to be in the same place, he admits, now that both are second homeowners.

“We have a little house in Provincetown, which is a very, very queer artist community at the very tip of Cape Cod in Massachusetts,” says Cooke. “We cut some of the Jerry Lee Lewis documentary up there. But Ethan is primarily in New York; Joel goes back and forth to northern California.”

Coen gives a histrionic sigh. “Life is a little sad,” he says. “You get old and established and have a second home. That’s a terrible thing that’s happened to us and to Joel. It’s like one of these saga movies where, when the guy is becoming successful, it’s interesting. And then there’s the part of the movie where he’s a big shot. At that point the movie is really dull. We’re like the establishment. It’s awful.”

I can only reply that I’m sorry to contradict you, Ethan, but: as if…

• Drive-Away Dolls is released in cinemas in the UK and Ireland on 15 March