When the Baroque movement in art ended, the backlash was severe. The very adjective became an insult: the cold, clear, rarefied eye of 18th-century Neoclassicism found its opulence stifling, its luxury oppressive, and its profusion of ornament, ugly. But the irony of the "purity" of Neoclassicism is, of course, that when it came to dissipated and depraved modes of living, the Romans really cornered the market. So, hearkening back to classical antiquity to rediscover "perfection" was perilous; only after much, much editing could the Romans (and Greeks) be sanitised enough to be "perfect". It is no wonder, therefore, that Monteverdi's The Coronation of Poppea lay hidden for more than two hundred years: it's Baroque, it's Venetian, and it has enough salacious vice to upset almost everyone. Interestingly, it was also one of the first operas to embrace real historical content; as our bitingly sarcastic and cynical Seneca (Piotr Lempa) might say, go figure.

This wonderful production by English Touring Opera with Michael Rosewell conducting the Old Street Band, beginning its tour at the Royal College of Music's Britten Theatre, does nevertheless give us a chance to see Nero in a fresh, if not altered, light. He is the sexual luxuriant and iconoclast, perhaps even an ambassador for freedom (approaching Mozart's Don Giovanni). Naturally, any freedom Nero gains for himself in this opera is purely and utterly selfish. It is an illustration of the inhuman ruthlessness of human desire; not quite a revalidation of the vibrancy of life and love. But we do see Nero, master of the callous scheme, burn with reckless lust; and while he orders public exiles and secret executions with his usual alacrity, he is terrifyingly, tenderly devoted to his mistress, at the expense of everything and everyone else. In short, it is not just the Nero we know.

Meanwhile, the Stalinist setting accords perfectly with what we do know of Nero's court: a place where secret machinations, sudden vendettas and violent outbursts were plats du jour. The fearful, uncertain, false reactions of the courtiers directly echo what we are told by Tacitus and Suetonius (and Robert Graves) of what life was like under Nero: mainly, it was nasty, brutal and short, even if he liked you.

James Conway's thoughtful direction for English Touring Opera brings Love (Amor, played here with a delicious mixture of naughtiness and menace by the marvellous Jake Arditti), triumphantly, to the fore. The Coronation of Poppea is, as Amor declares at its beginning and end, Love's own victory; a brilliant directoral touch at the end (watch Poppea's face carefully to the final curtain) tells us even our ostensible victors are vanquished by Amor's overmastering, obsessive, furious power. Love is the only character who survives this opera intact.

The Prologue sees imperious Love railing at dowdy Virtue (deftly sung by Hannah Sandison, also a compelling Drusilla) and gimcrack Fortune (the shimmeringly fabulous Hannah Pedley, later a brooding and vengeful Ottavia), as the goddesses squabble over who is more revered by mortals. Amor proclaims his absolute pre-eminence in the universal order, and announces that to prove it, he will trample them both in a day. As the fateful day begins, the faithful Ottone (sung with the most heartbreaking tenderness by Michal Czerniawski) waits outside Poppea's window; but in vain. Ottone is not Love's chosen hero: Nero (Helen Sherman, moving from burning lust to cool death threats with chilling speed) and Poppea (the endlessly bewitching Paula Sides) are in love – a mutual fascination of lust which pushes all other concerns out. Basic morals, Stoic philosophy, global politics; nothing can stop their passion. It is a recalibration of the Judgement of Paris: and just as at Troy, a whole society stands to lose this game.

Like Nero's court, this opera is both beautiful and deadly. The music is hypnotic; the sheer beauty of the final duet between Nero and Poppea ("Pur ti miro, pur ti godo") is astonishing. The orchestra, filled with period instruments, creates a lusciously atmospheric sound under Michael Rosewell's baton. But this beautiful world holds only compromised characters: weak, selfish, lustful, indulgent, insincere, proud, or cowardly. Drusilla, the virtuous and overlooked maiden, is pathetically self-deceiving; Ottavia, who has nobleness in spades, is not below stooping to ugly threats to get her own way; Nero, the ultimate lover, will go on (after the action of this opera) to kick the pregnant Poppea to death.

This does pose a problem for the gentle spectator, who may find it difficult to like any character enough to love this opera as it unfolds. There are further problems: the slightly clunky set leads to some distracting stage-business as moving walls wobble on their hinges, and while much of the singing is excellent, some of it is weak or strained, leaving a slightly uneven effect overall. But in the end – as in the world – Amor conquers us too. The sheer virtuoso brilliance of Nero and Poppea's last duet is a magnificent, unapologetic vindication of everything that has happened; and proves their love was too powerful to be denied. The death toll, horrific though it may be, is simply an appalling testament to the strength of that love.

So, go hoping for a rags-to-riches romance, and you may, I'm afraid, be disappointed (even disenchanted). But go for a masterclass in gender dynamics, psychological aggression and power play, possibly with a little insanity sprinkled in, and you will be: in celestial bliss. Which was where I left Nero, with his Poppea – as the curtain fell... This brutally amoral gem still has the power to shock, to stun – and to serenade.

Monteverdi: The Coronation of Poppea, at RCM, Britten TheatreCharlotte Valori reviews Monteverdi’s Coronation of Poppaea by English Touring Opera at the Royal College of Music4