The perfect tango demands a powerful erotic chemistry, so when the stars of Tango Por Dos split up, their act foundered too.
They are billed as ''Direct from Argentina'' but, like many troupes of national dancers, Tango Por Dos's artists spend the bulk of each year in a suitcase. A suitcase full of the double breasted suits and slit skirts that make up the average tango kit.

Last month it was Rome. The company visits regularly and the mellow beauty of the streets and the minky glamour of the women is a home from home for a dancer pining for the louche grandeur of his native Buenos Aires. Milena Plebs, 36-year-old artistic director of Tango Por Dos, smiles widely as she looks across the sunny hotel veranda to the Tiber. "I hate this place!" She may not feel so warmly towards it by the end of the day. Mine is the first of a long string of interviews, many of which are scheduled to focus almost exclusively on the state of play between Plebs and her co-star of 12 years, Miguel Angel Zotto.

Milena Plebs speaks excellent English but Miguel's is more hesitant. The promoter begins to panic when he realises that no interpreter has been booked. In the old life Milena always translated for Miguel but that may not be appropriate for a day of dirty laundry. Will I be asking any erotic questions? Sorry? What will I be talking about? Er, dance? The promoter seems faintly surprised by this. OK. So long as I don't want to ask Miguel anything too erotic Milena will consent to translate.

Plebs used to be one of the company's star dancers but that all ended last December. One of her chief reasons for hanging up her t-bar shoes was the fact that she could no longer bear to dance with Miguel. They split up in 1995 and for the first couple of years their on-stage relationship survived but eventually Plebs began to feel the strain: ''It's difficult when one of the two persons starts a new relationship. It became very stressing. I used to feel that dance was a big pleasure but in these last two years it felt like I was working.'' After 18 years of constant applause how can she bear to give it up? "I don't miss it yet. I dance socially and I choreograph''. Couldn't she find another partner? She looks at me as if I were mad ''But Miguel Angel Zotto is the best. If I dance, I dance with him. Otherwise? I don't perform.''

Which leaves Miguel with the difficult task of breaking in a new partner. He currently dances with two women in the show. Both very different, neither (as yet) ideal. ''One is very plastic and elegant but the other is very strong''. Dance is always perceived in cliches: ballerinas are anorexic, their partners are all big Judy Garland fans, Morris Dancers are educationally subnormal and tango couples are at it like rabbits. On Plebs's evidence the last one actually appears to be true. Tango Por Dos uses seven couples of which five are married. ''Usually the most famous couples have (or have had) a very passionate relationship. It's important because you have a strong feeling of pleasure with the other person''. Whether Miguel and his two Milena-substitutes are currently sharing feelings of pleasure is not something I feel able to ask - besides who would translate?

My first close look at Miguel comes after the company's show at the Teatro Olimpico. He's wearing a shortie kimono. He wipes the greasepaint from his face, ruffles his hair and loses about 20 years in the process. In costume the 39-year-old lounge lizard is a dead ringer for Carlos Gardel, the tango screen idol of the Thirties; stripped of the veneer of the sharp suit and brilliantine he is smaller, less impressive. This minor deity of the tango likes to make the warm bath of appreciation last as long as possible. After the show he showers, changes, and then what? A movie? A meal? No. Miguel goes dancing. Isn't he tired? "A little bit but I love dancing."

Imagine it. A tiny tango club in a foreign city packed with milongueras and suddenly in walks Miguel Angel Zotto. They're excited at having a star in their midst but Miguel is completely recharged ''If he's depressed he goes to these places,'' explains Milena. ''People give love to him and he feels good''. Yet in the milongas he must dance with strangers. Does that ever feel right? This time Miguel answers for himself ''Tango isn't just steps. It tells a story about two people''. Bad partnership is instantly apparent. ''It's always bad if she doesn't receive.'' Zotto allows an exquisite convulsion to pass across his shoulders to illustrate this failure to connect. It is a swift mime of struggle and resistance - the antithesis of a good tango partnership - which conveys the unease he feels in the wrong embrace. A woman's willingness to yield utterly to the commanding arms of her partner is central to the chemistry. This year's search for a new partner has shown how hard it is: it's not purely a matter of skill. ''There was a very good person but he said 'I don't feel her, she doesn't surrender' - and she was a great dancer.'' It seems that the spark between two people is impossible to predict until they take to the floor. Milena describes with a sort of awed excitement the feeling that envelops her when she's back on the floor ''I start dancing with a man I don't know and suddenly I feel a big energy between us."

They warn you about the tango. Take a couple of classes and it's more than a hobby; it's a way of life. Ask Sally Potter, who turned her evening classes into a feature film, The Tango Lesson. Potter (who stars in her own film) plays a British film director who takes tango classes with handsome young Argentines. Most critics agreed that the movie was an embarrassingly long love letter to herself but despite this, it proved that the hunger for tango is not an exclusively Argentine trait. It was well received in Buenos Aires as a film about the tango that didn't involve a slab of Lurpak.

The Japanese have been crazy for it since Baron Megata Tsunumi got the bug in Paris just after the Great War. He took lessons for three years then went home to Japan with a handful of tango records and the fever of an evangelist. Argentine tango is still huge in Japan, and so is the so-called "international tango", the kind seen in ballroom dancing competitions. But now the faster, sexier, Argentine variety is in the ascendant - even in Home Counties North. Milena Plebs has noticed a trend. ''In continental tango all the attention is in the torso and the head and the legs are doing basic steps, but they are incorporating more and more Argentine tango steps. They are trying to create a whole new competition category.'' Milena has noticed that some of the best non-Argentines come from unexpected places ''You find the best tango dancers in Europe in Germany and Holland - not in Italy, not Spain. They have their own feeling - and they have better teachers.''

Milena Plebs may no longer prowl across the stage in her high heels, may never again wrap her ex in the poisoned grasp of her fishnet thighs, but the tango is still her whole life. It's a dance that comes with a health warning: ''When you start to dance it you become obsessed''. Now she is looking for a life outside. ''I felt blocked by the embrace of the tango.''

Nottingham Concert Hall (0115-948 2626) to 9 April; The Hawth, Crawley, 11 April (01293 553636); Orchard Theatre, Dartford, 14-15 April (01322 220000); Theatre Royal, Newcastle, 16-18 April (0191-232 7076); Peacock Theatre, London, 20 April-9 May (0171-314 8800).