Simon Godwin’s Much Ado About Nothing is set in a steamy Italian holiday resort, the Hotel Messina, in the 1920s. A smart move, design-wise. The jazz age was one of those rare moments in history when every member of society, from the lowliest chambermaid to the richest aristocrat, dressed with impeccable style and flair. The show is stupendously good to look at it and it kicks off with a thrilling blast of rumba music from a jazz quartet on the hotel balcony. Even sceptics of jazz need not fear these players. The musical score is a triumph for one simple reason: there are no jazz solos.

The comic passages of the play are performed imaginatively enough although some of the stunts – the collapsing hammock and the dodgy ice-cream trolley – become a bit repetitive. Hero’s rejection at the altar and the plot to fake her death are done with real, heart-rending emotion. It’s unusual to see such deep passions emerging from these melodramatic scenes.

John Heffernan plays Benedick with a wonderfully relaxed informality. He’s strange to look at. Geeky, weak-kneed at times, but he happens to be tall and handsome too, with a nimble physicality. He strikes a perfect balance between the hero’s virile swagger and his melancholy, ruminative nature. You’ll wait years to see a better Benedick. Katherine Parkinson delivers Beatrice’s verbal bullets with impish drawling aggression – but she’s not always fully audible.

David Judge plays Don John as a taut, wound-up gangster with strong hints of Salford in his voice. Which is fine on its own, but it doesn’t suit the setting. How many Mancunian bad boys would you meet on the Italian Riviera in the days of Hemingway and Fitzgerald?

Eben Figueiredo plays the shifty, preening Claudio with a London ‘roadman’ accent. Perhaps he wants to make teenagers from south London feel involved. Two snags there: the NT is unlikely to attract droves of youngsters. And it’s Shakespeare: he makes everyone feel involved. Relax. He’ll do the work for you – if you let him.

The outstanding performance comes from Phoebe Horn, as Margaret, who draws the eye instantly whenever she appears. It’s rare to find a youngster attempting to upstage the entire cast of a mega-budget Shakespeare production. And it’s even rarer to see the ploy come off so beautifully. Horn shares long scenes with seasoned thesps and she dominates the action from a minor position. It’s a bit naughty pilfering the limelight like this but she earns every bit of the applause she wins. Nature has blessed her with the looks of Susan Hampshire and the comedy skills of Sarah Crowe. A star on the rise.

Freud’s Last Session, by Mark St Germain, is about a meeting between C.S. Lewis and Sigmund Freud on 3 September 1939. The date puts the characters under lots of pressure. They listen to Chamberlain’s radio broadcasts about Hitler. Freud makes anxious phone calls to his daughter, Anna. And the first air-raid siren causes them to panic as they realise they have nowhere to shelter.

But these external influences are artistically unsatisfying. A good drama should find conflict from within the characters and their relationships. The dominant theme is God. As a child, Lewis paid no more attention to Christianity than a ‘gibbon pays to Beethoven’. Freud’s broad-minded Jewish father allowed their Catholic nanny to take young Sigmund to Mass and to receive the sacraments. But with little effect. Freud wasn’t the first worshipper to be converted to atheism by Catholic priests. But he retained a lifelong fascination with religion, and his desk is crowded with effigies of gods from the Greek, Egyptian and Hindu traditions.

Lewis (Sean Browne) believes the Christian God wants us to perfect ourselves through suffering. To Freud (Julian Bird), that’s offensive. A child’s death or a terminal illness are surely evidence of God’s antipathy to mankind. And with Hitler on the march across Europe, the commandment of Christ to ‘love they neighbour’ is an instruction to support the aggressor. By turning the other cheek we enable the triumph of evil. How can that be good?

The script doesn’t flinch from the grisly realities of Freud’s terminal condition. The tumour growing in his jaw makes his pet dog scamper away in horror. He wears a prosthetic steel plate that causes him agony and he refuses to let anyone adjust it but his daughter. The pain increases and Lewis offers to improvise an emergency operation as Freud sits on his famous couch. So the couch becomes a dentist’s chair and Lewis turns into a nurse or even a surrogate child, like Anna.

This is an excellent drama of ideas. It’s deliberately discursive and lacking in spectacle or physical action. Well worth 90 minutes of anyone’s time.