Purveyors of literal theatre, the kind where a ship’s a ship and a castle has ramparts, will usually make a hash of Tristan und Isolde because Wagner appropriated the ancient tale for metaphysical rather than historical purposes. It is the most interior of operas, a conduit for life’s abstract compulsions: ardour, yearning and desire. At the basic level it’s an opera of hormones, not happenings; fathoms deeper it explores human experience at a point where sense is dumb and flesh retires – as close to heaven and hell as it’s possible to go without first having to die.

The tale of Isolde and her enemy, the warrior Tristan, with whom she becomes forever conjoined through the accidental administration of a love potion rather than a poison, isn’t about feuds and kingdoms, it’s about sex – ‘la petite mort’. Not that we need to see any onstage coupling; Wagner put all that into his music, closing in and magnifying it. It’s all there, larger than any life; but it remains unfulfilled – unlike its companion, death.

Director Pierre Audi is good at the former but less adept at the latter, which smacks of deleted scenes from Game of Thrones. (Jam in the knife! Ram home the spear!) Amid designer-primitive costumes and peasant wigs, Christof Hetzer’s sets have a jumbled aesthetic. Vast nautical bulwarks (Act I) give way to a Cornish dinosaur graveyard (Act II) and a chic stage-within-a-stage (Act III). Clean geometric shapes clash with the primitive like that earth-visiting monolith in 2001: A Space Odyssey, so much so that I half-expected Melot (Andrew Rees) to chuck a bone in the air.

Musically, though, this Glyndebourne-sized Tristan und Isolde at the Théâtre des Champs-Élysées is rapturous. Daniele Gatti conducts with tempo choices that border on the brisk, yet there are moments when he draws out motifs and luxury moments (the Tristan chord!) to impossible lengths. On paper that appears self-indulgent; in performance, time stood still. It helped that the playing of the Orchestre National de France was distinguished, with Laurent Decker’s cor anglais solo in the final act the most hypnotically exquisite I’ve heard. Small wonder Gatti beckoned him onstage at the curtain.

The eponymous pair are so well matched that it’s hard to believe Rachel Nicholls was only brought in as a late replacement when Emily Magee withdrew after three weeks of rehearsal. You’d never know it. She and Heldentenor Torsten Kerl complement each other with unforced vocal beauty: they sing the score with a complete absence of excess baggage. There is no squall or big vibrato or weighty ‘monster’ singing, just unflagging power and, where needed, reserves of volume produced with astonishing clarity. Christian Thielemann recently described Wagner’s characters as “a crazy couple hovering on the verge of what is humanly possible”, but these two take it in their stride.

Kerl, despite a tendency to screw his eyes into a snarl during the big moments, brings lyrical sweetness and pathos to his role; Nicholls marks her ascent to the Wagnerian top table with singing of a limpid ecstasy that recalls Margaret Price in the Carlos Kleiber recording (although Isolde was a role Price never dared assume in live performance). Their erotic duet in the second act is ineffably moving – a highlight of the year in music.

Indeed, every cast member sings with impressive technical and idiomatic command. Audi’s probing way with the secondary characters helps sustain dramatic interest, with only the excellent Rees’s Melot stuck in a two-dimensional existence as the voice of poison, crippled both in form and nature. Michelle Breedt is a haunted, troubled Brangäne, Brett Polegato’s soldierly Kurwenal a staunch ally to Tristan (you’ll easily imagine him carrying the burly Kerl on his shoulders to the boat) and Steven Humes an uncharacteristically humane King Marke, driven more by sorrow than anger.

I take issue with Audi’s closing flourish, though. He presents Nicholls in severe silhouette for the Liebestod, completely still and facing out, as though transported from the human drama to somewhere entirely other. That, surely, is the wrong story. Isolde’s song of ecstasy is too human to be sung from beyond the grave: it transports her towards death; it doesn’t arise from the memory of life.