ON A Saturday afternoon in February, a month before “Macbeth” was to open at the National Theatre in London, its artistic director, Rufus Norris, rehearsed alone with Rory Kinnear. Dressed in jeans and trainers, Mr Kinnear heaved a battlement across the studio. On Mr Norris’s cue, he became the thane, hand clutched to his pate in anguish, eyes aglow.

The session’s aim, said Mr Norris, was to find an approach to Shakespeare’s soliloquys that fitted the Olivier Theatre, the National’s biggest. For all the brawling and sorcery, at the play’s heart are the lulls in which Macbeth mulls the witches’ prophecies and the crimes they incite; in which he decides what kind of man he will be. These are intimate scenes, and finessing their gestures and tempo was intimate work, like a clinch between prizefighter and trainer. “It’s less literal,” Mr Norris said of the dagger that Macbeth hallucinates before killing Duncan, the old king. Grab higher, he told his star.

It helped that Mr Kinnear was well-acquainted with the Olivier’s stage. As Hamlet in 2010 he smoked a cigarette on it during “To be or not to be”. In 2013 his Iago filled the theatre with his resentments. The finest Shakespearean actors are more than entertainers: they are standard-bearers of a national identity and culture, and indeed of culture in general. Mr Kinnear’s preparations and career offer an insight into the demands of that specialised, storied craft.

“Macbeth does murder sleep,” a line delivered soon after the regicide, turns out to be true in more than the obvious, conscience-stricken sense. With every play, said Mr Kinnear a few days later, “you try to delay the point when your entire life is consumed by it.” Now, he conceded, “it’s time to give in.” Anne-Marie Duff, his Lady Macbeth, describes him as “fantastically playful” and “dangerously funny”. He is also single-minded, driven by an inkling that “there’s still more to discover, there’s something I’m missing” in the part.

The future in the instant

If dedication is one requirement, Mr Kinnear’s performance in “Othello” showcased another talent expected by modern audiences: the ability to make plausible human beings of 400-year-old characters. Often Iago is a cartoon of evil; his was propelled by a class grudge and as recognisable as a neighbour. “That version of Iago was Rory’s from top to bottom,” says Adrian Lester, who played the Moor. In “Measure for Measure” at the Almeida Theatre, also in 2010, Mr Kinnear’s Angelo—sometimes a monstrous prig—was a man tragically outmatched by his own feelings. Gimmickry and special effects are the obvious way to make Shakespeare feel contemporary. This kind of psychology is harder and more effective.

“What is it about these people who are drawn to the top of the pyramid?” Mr Kinnear asked of the Macbeths in a break between rehearsals. In his reading, post-traumatic stress contributes to their cruelty. “The things he must have seen,” he said of all the bloodletting; “the things he’s been required to do.” Macbeth, he noted, always has somebody to blame, fate or the witches or his wife. And yet, Mr Kinnear said, breaking into a soliloquy, atrocity “brings out something utterly gorgeous in him”. Shakespeare is “always seducing the audience to the dark side”; in Macbeth’s case, “it’s the blackest desire within him that summons up the greatest poetry.”

The poetry is Shakespeare’s biggest challenge, both to actors and to audiences. Hammy magniloquence risks alienating viewers, not just for an evening but for life, as does obscurity. As Tiffany Stern, of the Shakespeare Institute at the University of Birmingham, says, great verse-speaking—honouring both the sense and the music—is a skill that other kinds of acting do not involve. One venerable shortcut, dating at least to David Garrick in the 18th century, has been to ditch tricky passages.

Mr Kinnear’s goal is to make the iambic pentameter seem as vernacular as artificial. “He can speak Shakespeare as if it’s his first language,” says Nick Hytner, who directed “Hamlet” and “Othello”. Usefully, Mr Kinnear saw lots of Shakespeare as a child. His mother is an actor, as was his well-known father Roy, who died after a film-set accident when his son was ten—too early to see Rory’s schoolboy appearance in “Cyrano de Bergerac”, the moment he thought “maybe this is my thing.”

With these cerebral abilities, says Ms Stern, Shakespearean actors need a “physical litheness and grace”, as Laurence Olivier epitomised. The plays, after all, were “written for whole-body acting,” not “a twitching eyebrow and bobbing Adam’s apple”. Mr Kinnear (now 40) has some of that mime-artist’s ranginess. His slouch said as much about his Iago as his lines.

This physicality is a bigger asset in the theatre than on camera, with its capacity for close-ups. Tellingly, perhaps, though Mr Kinnear has featured in television dramas and as a spy chief in recent James Bond films, he is most recognised for his stage acting, and is fervent about it. Theatre is an expensive and risky art-form; it can seem clunky, even moribund, in a world of digital entertainment. But, he said, nothing else elicits “the exchange of energy that you get at live performance”, a connection even more valuable in an automated age. Screens can never match the electric sense that “no one else gets to see what you see.”

Citing some of the practitioners he reveres—Anthony Hopkins, Albert Finney, Michael Gambon—he added an abstract quality to the job description, a mysterious amalgam of ethics and charisma. A role “is just a prism” that “reveals who you are as a person”, he argued. “You become drawn to actors’ souls.”

The last syllable

“Macbeth” opened this month, one of several current productions of the play in Britain. Its timeliness is glaring. In the story, the wrong people are in charge. The same attributes that propel them to power leave them wholly unsuited to wielding it. Macbeth’s misdeeds make him paranoid. “To be thus is nothing,” he says bitterly of the status he once coveted. “But to be safely thus…” Yet he misses the real threats against him, blundering to his doom as accusations of treason proliferate. “There’s not a second where he shows any enjoyment in being king,” Mr Kinnear observed.

A new stiffness in his gait projects this tension on stage. Between the combat and decapitations, Macbeth’s horrified shaking, his cowering in the face of Banquo’s ghost and cradling of his wife’s corpse, Mr Kinnear’s is an all-action turn. But its strength lies in quieter gestures—a rub of the head, an anxious stroke of the ear. His body relaxes again only when he arms for his last fight, like an embattled politician rediscovering his mojo at a rally.

Just as his Hamlet was a familiar (if hyper-intelligent) depressive, his Iago an improvising punk, his Macbeth is a simple soldier in a brutish world, carried away by the logic of ambition. His tone is as demotic as his verse is precise. “It was a rough night,” he says after stabbing Duncan, like a man recovering from an all-night party.

In the scene that precedes the murder he reaches high for the spectral weapon, as Mr Norris had urged. His hand thrashes the air, but as he asks the famous question—“Is this a dagger which I see before me?”—he smiles as if greeting an old friend.