Adrian Blue and Catherine Rush have an easy demeanor that belies the pluck of the work they are developing for debut tonight at the Vineyard Playhouse. Theirs is a kinetic energy, all quick smiles, snappy repartee and dynamic gestures. She does the talking, in spoken English, for both; "AB", as he is known, speaks with his hands, his face, even his space, because he is profoundly deaf.

None of the actors in the couple's play, This Island Alone, was available to interpret today, so Ms. Rush is doing double duty. She makes apologies for this. Sign language and spoken English are separate languages; you cannot do both properly at the same time. Yet most of the professional actors in this production have been asked - and have agreed - to do exactly that on stage.

"There is a sensitivity issue," concedes Mr. Blue, who has performed and directed with National Theatre of the Deaf as well as other theatre, film and television projects.

For many in the deaf community, language has grown into an increasingly complex and political debate. Casting a deaf actor in a current Manhattan production of Sam Shepard's Buried Child, where Darren Fudenske speaks but does not sign, prompted director Stephanie Barton-Farcas to tell the New York Times last week that "some deaf people do not believe that deaf people should speak at all."

According to Mr. Blue, the play he has cowritten with his wife, Ms. Rush, called This Island Alone, is for the actors "a full challenge." And, he adds, for the writers and director too. The unusual choice to have actors speak two languages simultaneously turns what might have been a simple history play into something ground-breaking in contemporary theatre. But it is the history that demands it.

The new full-length play is set on one the earliest known deaf communities - Martha's Vineyard.

In 1854, when the Island's deaf population peaked (the play is set in 1898), the American national average was one deaf person in nearly 6,000, while on Martha's Vineyard hereditary deafness made it one in 155, according to a report by Jamie Berke. In Chilmark, where most of the deaf people lived, it was 1 in 25, and in Squibnocket, as much as a quarter of the population of 60 was deaf. The result was that Islanders thought deafness was no more remarkable than green eyes or blonde hair.

Because Islanders routinely spoke and signed simultaneously - one character says, "Wait, I forgot, is he deaf or is he hearing? I can't remember" - the playwrights deliberately put themselves into this self-described daring position.

"It's carefully choreographed to make it work, because that's how people actually lived here in Martha's Vineyard," explains Mr. Blue, who is directing. "There weren't two separate languages here... Once you moved your mouth, your hands moved with it."

In This Island Alone - different, though inspired by a shorter play, A Nice Place to Live, which the couple wrote for Boston's Wheelock Family Theatre and workshopped at the Vineyard Playhouse in 2004 ­ - the two languages follow each other. Some lines won't be voiced, they will just be signed. Sometimes spoken lines will not be signed.

"There are moments when a deaf audience might be lost, but they will be caught up within the next scene, or moments where a hearing audience might be lost, but they will be caught up in the next two lines," he explains between his and Ms. Rush's bites of tuna wrap. "That is a true experience for any person who isn't speaking the same language."

The play is not written in English and then rendered visual, as was a production of Shakespeare's Twelfth Night the couple was involved in at Yale University. Nor is it performed in English and then interpreted, as selected performances of Buried Child will be. As Mr. Blue told National Public Radio last week of his choice: "I want to see the truth of what is going on in an intellectual way put into both languages simultaneously."

He explains that, "We create the story, she writes the English."

Ms. Rush picks up: "Yes, but when it comes to translating the English into the gestural language that we use for Martha's Vineyard [the play modifies American Sign Language to suit the period], AB does that, so it is equal in the writing.

"It's just on the page we see my work. But on the stage [it is] not just his directing, you will see his words in sign language."

Because sign language is not a written language, the couple are videotaping some of the lines, so that a sort of a video script of the sign language part of the play can be developed.

Ms. Rush says the play is unusual in the prominence of the signing. "Very often in theatre that is signed - and I don't know if it is because most of the time the director is a hearing person - but the sign language is made second to the spoken language.

"In this, because AB is deaf and visual, the sign language has to keep an equal footing with the English," she says.

"What is also nice for the two of us, because we are a deaf and hearing couple, is that the English is important to me and the signing is important to him, so the two of us are unwilling to give up... the artistic values of our languages. So we have to find a place where they can meet, and that produces an artistry, I think, that is very unusual. We both respect each other a great deal - and we are both very stubborn."

It is entirely appropriate that the production is theatrically contentious, because it deals with a divisive moment in the politics of the deaf community on the Vineyard and beyond. Ms. Rush: "It's based on oral history [describing an] off-Islander who came to a town meeting and asked, are the deaf and dumb allowed to vote?"

No one ever had asked that question. Mr. Blue: "It was offensive, but it had to be explored."

In the play, best friends for decades, one hearing and one deaf, fall out over the question. The deaf man argues there is no point finding out; the deaf always had voted. The hearing man argues they must investigate whether there is a law against it, because the law is the law. "This," sighs Ms. Rush, "over an issue that never was before."

Mr. Blue says deaf people look at this period of history in Martha's Vineyard with a broken heart. "Because this is an era and a way of life that died and just has never existed since - where people signed and spoke, and deaf didn't feel identified as deaf people, or handicapped people. It just was a language barrier.

"Many of us wish that America was the same way. I could go to a public high school and I wouldn't need an interpreter. My teacher, my friends, everyone would sign, all of them would be hearing. How cool would that be?"

Ms. Rush can hear; she learned sign language just because she wanted to. "And I am not one of those, like, learn-language gals, you know, ‘Oh I want to take up Italian!'" she says. "I just wanted to learn sign language, and I didn't know why. It didn't make any sense to me."

Even after her teacher died, she kept doing it.

"I would practice by myself," she says. "I had no deaf friends, I didn't want to be an interpreter, I didn't want to help the deaf. I just wanted to learn. So I followed that desire.

"Two years later, I got hired to design costumes for Adrian, and I won't say that immediately I went, ‘Oh! This is why I learned sign language,' but I can tell you now, if I didn't know sign language I never would have met him and we would never have been able to have a conversation on... any deep level.

"So I think that I learned sign language just so I could meet him. That's what I think."

The seminal book about the deaf community on the Vineyard, Nora Groce's Everyone Here Spoke Sign Language, showed that what now is labelled a handicap is nothing more than a linguistic barrier.

Ms. Rush: "When a community makes a minor adjustment to the way they conduct their life" - and perhaps when one woman does the same - "it's profound."

This Island Alone will have staged readings appropriate for families tonight and tomorrow night, Oct. 20 and 21, at 7 p.m. at the Vineyard Playhouse. General admission tickets are $15. Each reading will be followed by a short question and answer session with the writers.