We live in an apparently transparent age. As Steven Spielberg said in an interview on the release of his film Bridge of Spies, which is set in the Cold War, “everyone is in everyone else’s bananas”. We live now in a time of near-total surveillance – almost everyone has a phone with a camera and an internet connection.

Social media capture the first spark of public opinion – something funny, more often something outrageous, occasionally something kind – whip it into a viral trend, and the flame grows with increasing intensity until it spreads around the world like wildfire.

This takes place in a matter of seconds. Like a murmuration of starlings, the swell of public voices can change shape seemingly of its own accord, with a newly reinforced power – at times to celebrate and unify, at others to humiliate and divide. It’s a miracle that there are any secrets left. Everything is everyone’s business. Which begs the question: in today’s world, how could one possibly get away with being a spy?

John le Carré has been as much the architect of our understanding of the world of spies – their milieu and their mystery – as he has been among the most sophisticated analysts of the British psyche and the creator of the most thrilling novels of the past half-century. For many, he is the primary interpreter of the reality of the Cold War.

The backdrop to his fiction was the state of political and military tension sustained between the US-led West and the Soviet-led East from the end of the Second World War until the fall of the Berlin Wall in 1989. Although both sides never engaged in full-scale combat, each was prepared for the possibility of all-out nuclear war, with the ever-present threat of mutually assured destruction.

This pervasive atmosphere of fear is woven into the fabric of le Carré’s great Cold War novels. His quiet heroes – Alec Leamas in The Spy Who Came In from the Cold, George Smiley in Tinker Tailor Soldier Spy, Magnus Pym in A Perfect Spy – were flawed, full of doubt, haunted by moral ambivalence, by their conscience, by the hypocrisy of having to do bad things for a greater good.

It’s a world now familiar to millions of readers: Savile Rows suits, code names, the “Circus” – le Carré’s name for MI6 – basement flats in Pimlico, safe-houses in Paddington, and back-stairs committee rooms in Whitehall. A world of paranoia and intrigue and secrets, far removed from the world where everyone knows everything about everyone else – the world we know today.

Or is it? To my mind, it feels as though there are still so many secrets, so many private conversations behind closed doors in the corridors of power. I don’t doubt that the business of government and the intelligence and security services remains undisclosed in the interests of national security and international relations. But their work remains opaque and mysterious.

Prime Minister David Cameron called a vote in Parliament on whether Britain should participate in air strikes against Islamic State in Syria, in the wake of the attacks in Paris, notably at the Bataclan concert hall. We were assured by our representatives on both sides of the House that air strikes would be reinforced on the ground by 70,000 moderate Sunni forces.

This intelligence, we were told, had come “from the highest level”, and was presented as conclusive evidence of the legitimacy and validity of the Government’s decision to send in British aircraft. This intelligence may never be disclosed to the British public.

About such things, we remain in the dark. We have been here before.

But the crucial reference in Parliament to the work of the security services, at such a critical hour, hints at the important and dangerous nature of intelligence gathering in today’s world. There is, behind the curtain, a complex network of interests and relationships, upon which depend our national security. This milieu is le Carré’s métier.

The action of The Night Manager takes place in the present. I play Jonathan Pine, a former British soldier with a service record in the Iraq War of 2003, who is discovered working as the night manager of a hotel in Zermatt, Switzerland, and is recruited by an intelligence operative named Angela Burr (Olivia Colman), working on the fringes of MI6.

Pine is sent in to infiltrate the inner circle of British expatriate Richard Roper (Hugh Laurie), who is selling British and US certified weapons to the highest bidder in the Middle East, and is (literally) getting away with murder. Richard Roper, in le Carré’s words, is the ‘worst man in the world’.

On the face of it, the political backdrop of The Night Manager bears little resemblance to Smiley’s world, but there are striking similarities. We no longer fear the outbreak of nuclear war between East and West, but we now have other forces of enmity and darkness, which give us even greater cause to be frightened.

Our enemies in the past decade have presented themselves in the form of extremist jihadist groups – the criminal anarchy of al-Qaeda or the barbaric evil of Isis, and the ground seems continually to shift beneath our feet. In the attempts of the allied powers of the West to confront these new threats, they take on the character of a terrifying, many-headed Hydra: chop off one head and two more will grow back in its place. The world is as dangerous as ever.

John le Carré’s anger is righteous in this respect. One can sense the writer’s rage that a man such as Richard Roper, recipient of a British education and inheritor of all the freedoms of British democracy, uses his privileges and the benefits of his inheritance to do the worst things imaginable.

He finances a life of luxury – yachts, jets, villas in Majorca – from the criminal sale of the most dangerous chemical weapons on the market, without a care for those who may become the victims of those weapons. Richard Roper trades in death, profits from it, and laughs.

There is no doubt he is charming: the devil plays all the best tunes. But he is a cynic and a nihilist and a psychotic, who has completely divorced himself from the consequences of the violence from which he profits, and lives according to his own law.

And the spies? The nature of information sharing may have changed in the digital age. The riots in Cairo during the Arab Spring uprisings of 2011, which brought about the resignation of former Egyptian leader Hosni Mubarak (the opening scenes of The Night Manager), were mobilised through Facebook, but the innate courage and the skillset of the spy remain the same.

A spy must possess an almost unnatural ability to dissimulate, to hide in plain sight, and a capacity for self-effacement and self-invention, which in itself is dangerous. We construct our identity and self-esteem by telling the story of ourselves to ourselves, and we reinforce that narrative with the reflections we receive back from the outside world, from our family and our friends.

A good spy suppresses that self (almost to self-denial) and extinguishes that narrative, accepting and embracing the mutability of identity and the malleability of public personae. But when all is said and done – after so much self-erosion – is there anyone left on the inside? All of le Carré’s protagonists, from George Smiley to Magnus Pym to Jonathan Pine, can be identified by their vulnerability, their loneliness and their doubt, but also by their defiance and perseverance – to continue to work in the service of a cause, in spite of immense risks to their health and security.

Jonathan Pine is described in le Carré’s novel as a “sometime army wolfchild, perpetual escapee from emotional entanglements, volunteer, collector of other people’s languages, self-exiled creature of the night and sailor without a destination”.

Richard Roper’s misanthropic misdeeds light a flame within Pine that provides him with a destination: a certainty, a moral integrity, which later gives him inner conviction and self-definition behind the exterior performance of his many personae. He’s an immaculate performer – but he’s on fire on the inside.

John le Carré’s heroes – while riven by doubt and isolated by their secrecy – become heroic by virtue of their self-sacrifice for the greater good. In The Night Manager, le Carré supports Burr and Pine’s pursuit of Richard Roper and the means by which they pursue him, because he sees and admires the essential courage in their call to action. As Martin Luther King said: “He who passively accepts evil is as much involved in it as he who helps to perpetrate it. He who accepts evil without protesting against it is really cooperating with it.”

Angela Burr and Jonathan Pine choose to protest against the evil of Richard Roper in the bravest, most dangerous way imaginable. Pine must live, under cover, within the jaws of the beast, knowing that they could snap shut at any time. And if ever that cover is blown, he’s a dead man.

The Night Manager begins Sunday 21 February at 9pm on BBC1