ON THE bare wooden stage of the Teatro La Fenice in Venice, Penelope, Queen of Ithaca, strikes a defiant pose. This is the moment of messy revelation in Monteverdi’s 1640 opera Il ritornello d’Ulisse in Patria. After 20 years, our hero Ulysses (though arguably Penelope is the true hero of the drama) has returned to Ithaca disguised as a beggar, has been jeered for his poverty, has not yet been recognised by his wife. When Penelope challenges her grim suitors to prove their strength by using her husband’s bow, not one can even hold it, let alone live up to all their macho talk. Only the gentle beggar can lift the weapon, and he proceeds to slaughter the lot of them to the sound of triumphant thunderclaps from Jupiter. Are we to rejoice?

In John Eliot Gardiner’s production there is no bow, no dark, broad sea of Ithaca, no gory killing spree. Lucile Richardot’s splendid Penelope is dressed in a simple brown tunic with just her body language (dignified) and voice (intensely, magnificently shaded) to communicate the hurt and stoicism of two decades’ faithful waiting. “No props,” Gardiner stresses. “Everything stylised, nothing literal. These operas speak to us most directly if we allow our imaginations free rein to listen and make up our own cinematic images.”

So what kind of inglorious images should we conjure while watching a hero wreak brutal revenge? I’ve always had a problem with this part of the Ulysses/Odysseus legend – what message do we take from the violence? – but for Gardiner, these moments of moral clash provide the power and contemporary relevance of Monteverdi’s operas.

“Ulysses is outraged,” he says. “Of course he is – the suitors have basically tried to gang-rape Penelope. He reacts and Monteverdi doesn’t avoid that reaction. Sure, a more noble response might have been peaceful or forgiving. What happens is not pleasant, but it is true to life.”

Besides the staggering music – and the music is staggering: bold, pliant, intimate, radical – it is the dramatic realism, the take-down of heroes, the levelling out of gods and men and women and rich and poor that make Monteverdi’s operas timeless. Two centuries later, Lord Tennyson would pick up on the same scarred humanity: that which we are, we are.

There is similar fallibility and botched morality in Monteverdi’s two other surviving operas, which together form a trilogy that Gardiner has been touring all this year with his Monteverdi Choir and English Baroque Soloists: their next stop is Edinburgh in August. L’incoronazione di Poppea (1643) depicts a sordid throng of power and lust with a title character who stops at nothing to get her way. Forget scruples, says Gardiner: “it is political ambition and sheer carnal, sexual lust that triumphs in the end.”

In Monteverdi’s earliest opera L’Orfeo (he called it a "favola in musica" – a "fable in music") we meet an erratic rockstar, a celebrity who is every bit as messed up as the celebrities we routinely deify and topple today. “This Orpheus is essentially a charismatic musician,” according to Gardiner. “A proto-rockstar – a semi-deo. But he is also a self-centred mortal who is only heroic and god-like in fits and starts.” Sound familiar?

Gardiner suggests that people are drawn to Orpheus “as much because of his weakness and insecurity as by his charisma.” Think, he says, of the crux moment when Orpheus turns to check whether Eurydice is behind him. “That silly little tune at the start of their walk” – he sings it, bouncy and flippant. “Isn’t it cocky? And then the panic sets in. It’s all so… so recognisable. These people are just like us.”

Monteverdi would become a priest in the 1630s, and many commentators have noted that he stepped somewhat out of party line by portraying dodgy human foibles with such obvious empathy. But he lived a life, too: around the time he was writing L’Orpheo (1607), he lost his wife and his favourite singer.

“With Monteverdi,” says Gardiner, “the eroticism is always tinged with nostalgia.” What’s more, Monteverdi lived at a time when the great thinker-scientist-artists were beginning to pursue the whole spectrum of human experience – the grotty and complicated as well as the chaste and noble. It was the age of Shakespeare and Caravaggio and, like them, Monteverdi gave integrity to the low lives as well as the high. He was a Renaissance man who investigated the science of how people behave and why – and then figured out how to communicate that through art.

So how does he? We could go into all kinds of technicalities here. Gardiner has written about “the use of traditionally forbidden intervals and harmonic twists that disturb the balanced style of Renaissance polyphony,” the “structural devices that can bind the narrative together.” He has pointed out how Monteverdi “veers away from the old modal systems and inches towards what we now recognise as tonal harmony.”

For me, experiencing Gardiner’s take on the trilogy in the immediacy of La Fenice, just streets away from where Ulisse and Poppea were first performed, what struck me most was rhythm. The dialogue in these operas is conversational and true-to-life, as passionate and irregular as any furious, love-charged speech. Gardiner tells me that not only does he insist his singers understand the Italian text, but also his continuo players – and it shows. The musicians who accompany the recitatives are utterly involved in the warp and weft and urgency of the storytelling.

When it came to casting, Gardiner’s initial idea was to use only native speaking Italians, but after auditioning for two years he “had to cast a wider net,” he admits. The results are superb, with an ensemble of nimble, subtle, vivid singers who take on various roles across the three operas. They come from Poland (tenor Krystian Adam), Korea (countertenor Kangmin Justin Kim), the Czech Republic (Hana Blazikova), the UK (soprano Anna Dennis) and numerous other countries.

“In the end I realised it doesn’t matter what their first language is,” Gardiner says, “because the study they put into the text is so intense. Sometimes native speakers can be lazy with their own language. It’s like when the Monteverdi Choir sings in English. Actually, we’re better in German or French.”

What was he searching for during those two years of auditions? What makes a Monteverdi voice? “Clarity and purity,” he replies. “A real sense of the language – not just pronouncing it correctly, but savouring the rhythmic eccentricity of Italian. An ability to create tension by tugging at the vocal line while the continuo plays the downbeat straight. A capacity to embellish with flair, like a jazz musician. And a sense of radar. How to melt into the ensemble, how to become neutral when necessary.”

When they started rehearsing, he tells me, they sang madrigals for the first several days. The impact of that is palpable, too. The music of Monteverdi’s madrigals is ultra-vivid, ultra-expressive, wrapped around words with ultimate synchronicity. Solo voices emerge to deliver supercharged emotion then blend back into the group. “That’s the stylistic reference point in these operas,” says Gardiner. “It always comes back to the madrigals.”

But there are still more reasons for using the same group of singers across the three operas. Gardiner has written about Aristotle, who “traced the origin of drama to the moment when the leader of the dithyrambic chorus stood apart from his 50 men and boys and began to sing back to them. This formed the basis of the oppositional stance which allowed tragedy to embody conflict rather than merely allude to it, and it later to became a vital creative device […] already present in L’Orfeo from the moment Monteverdi and his librettist make room for individual shepherds and nymphs to step out from the chorus, comment on the action and then retreat back into its ranks.”

It’s a neat trick. By having his singers shape-shift, Gardiner gets the best musical blend from his forces, reminds us that one personality can have many sides, streamlines the touring company’s finances – and nods to the most ancient of ritualistic dramas.

The orchestra isn’t exempt from all this. The role of the instrumentalists is “by no means to be anonymous,” Gardiner explains.

“They are the engine room of the drama.” They sit centre-stage and the action happens all around them. Periodically a singer will pester or berate or caress one of the players, and at one point I noticed the two flute players knitting during several bars’ rest. “Ah yes, the knitting,” Gardiner confirms. “I spotted them doing it in rehearsal and it occurred to me to feature it. All those years Penelope was waiting for Ulysses, she would weave a tapestry then unpick it every night. So that’s what I asked the flute players to do.”

There’s something niggling me about the trilogy coming to Edinburgh. Everything we’ve discussed so far relies on up-close involvement from the audience. These operas were never meant for the grand stage, after all – the first performance of L’Orfeo wasn’t in a hall at all but in a room, where the signers addressed the guests of the Gonzaga ducal palace in Mantua directly and intimately. The Edinburgh International Festival has scheduled the Gardiner performances at the Usher Hall, presumably to up ticket sales. Will anyone sitting in the gods get the crucial grain and nuance? “I have no idea,” says Gardiner, not words usually associated with him. “But it does feels absolutely right to be doing these operas now,” he adds, changing tack. “The blatant power abuse, the reminder that heroes can get it wrong. Didn’t you feel that watching Poppea?” he asks.

“For me there’s a real Donald Trump-ness about Nerone. The seediness and the corruption. The hysteria and the paranoia. I’ve been constantly struck by that.

"God,” he exhales. “How relevant it still all is.”

L’Orfeo, Il ritorno d’Ulisse in patria and L’incoronazione di Poppea are at the Usher Hall, Edinburgh, on 14, 15 and 17 August respectively