The Secret Agent, the modern period drama filmed in Scotland

The Secret Agent. Photographer: Des Willie/BBC

Suicide bombers, radicalisation and counter-insurgency. Self-serving political hypocrisy, fury at bankers, Russians flexing their muscles in London and a vulnerable young man groomed to carry out a terrorist outrage. Joseph Conrad’s 1907 novel The Secret Agent might be set in 1886, but its relevance to the present day could hardly be more striking.

Certainly, the book’s cultural legacy is pronounced. One of the most oft-cited works of literature in the wake of the 11 September attacks, the statement “Exterminate. Exterminate”, uttered by the nihilistic Professor, is said to have inspired the Daleks’ battle cry in Doctor Who. More soberingly, the Unabomber, Ted Kaczynski, was an avowed admirer who thought that his family couldn’t understand him without reading Conrad.

Perhaps too, with the abuse of immigrants currently making headlines in the wake of the EU Referendum, it’s also worth recalling that the novelist himself, creator of the hugely influential Heart of Darkness, Nostromo and Lord Jim, was a Polish émigré, whose friends and peers such as Ford Madox Ford, HG Wells, Rudyard Kipling, Virginia Woolf and even his wife, Jessie, never truly accepted as English.

Now The Secret Agent has been adapted into a three-part BBC drama. Starring Toby Jones in the title role as Verloc, employed by both the Russian embassy and Scotland Yard to spy on the anarchist cell that gathers in his Soho sex shop, it co-stars Line of Duty’s Vicky McClure as his unsuspecting wife Winnie and Boardwalk Empire’s Stephen Graham as the man charged with monitoring him, Chief Inspector Heat.

When the Russians demand that Verloc bomb the Greenwich Observatory, so that the anarchists are blamed and the British authorities crack down on civil liberties, he turns first to The Professor (Ian Hart) to build him an explosive device, and then Winnie’s mentally ill brother Stevie (Charlie Hamblett) to be his accomplice.

Notwithstanding a few scenes shot at landmarks like the observatory and Trafalgar Square, most of 19th century London was recreated in Scotland’s Central Belt, with Glasgow’s City Chambers becoming the Russian Embassy and Edinburgh’s Thistle Street the bustling Soho alley outside Verloc’s shop. The interior of this seedy establishment has been erected in a shed in the grounds of Newbattle Abbey College in Midlothian, stuffed with Victorian erotica and prominent sex toys, and I’m watching the filming of Winnie welcoming the anarchists into her home. The impassioned Yundt (Christopher Fairbank) stabs a knife into his chair’s armrest, sending the sensitive Stevie into paroxysms of panic. And Winnie shares a lengthy, lingering glance with the handsome Ossipon (Raphael Acloque).

Like Conrad, who was inspired by French anarchist Martial Bourdin’s failed attempt to blow up the observatory in 1894, the drama’s writer Tony Marchant reckons Winnie is the most important character in the story. He’s made her attraction to Ossipon more overt “because it has to feel like a genuine love story” he explains. “Her tragedy is that she always hopes. She hoped she’d have a life with Stevie, she hoped that her marriage would be OK … and she hopes that her relationship with Ossipon will work out.”

“She’s all heart really, she just wants the best for everybody” says McLure during a break from filming. “She’s a mothering character, even though she’s not actually a mother … [her’s] is a functional unfunctional family.”

Unfortunately, Winnie’s love for Stevie is so powerful that she herself becomes a “ticking time bomb”. Repressing her worries about Verloc, “she’s forever trying to block out the bad stuff. She has this line she says a lot: ‘It doesn’t bear too much looking into’. ‘Let’s not delve too deep’ ...”

Marchant has harnessed Conrad’s allusions to scientific progress and modernity, symbolised by the Greenwich Observatory and the uncivilised assault on it, for the drama’s energy. “It needs a kinetic approach, it’s got to be constantly moving forward”.

While the novel is a non-linear satire, full of irony and related from various character’s point-of-view, Marchant and director Charles McDougall have fleshed out some of the the caricatures and sought a more direct emotional investment. “There’s a lot of scorn in the book and not enough pity … there has to be consequences, the domestic tragedy more felt,” the writer says.

Fundamentally, The Secret Agent is now a thriller. Not only do Verloc and The Professor, “the first suicide bomber”, never actually meet in the book. But Marchant has also given the latter his own scene on an omnibus, sitting with his bomb in his jacket, confronted by the desperate Heat in a clear echo of the 7/7 atrocity in Tavistock Square.

One irony that has been retained is the story’s title. Conrad heavily influenced John Le Carré. Yet Jones, who starred in the 2011 film version of Tinker Tailor Soldier Spy, points out that Verloc “doesn’t seem to have any agency at all, he seems to be completely at the whim of everybody else”. Pressured by his fellow anarchists, by his obligations to his family, by the Russians and by Heat, “at times, the anxiety as an actor is are you doing enough? But the story is happening around him, he is reactive. So I suppose that’s the challenge … I’m reacting to the pressure.”

For Marchant, while The Secret Agent is about “terrorism and the mindset of people who actively wish to bring down corrupt western society … it’s also about the geopolitical [manoeuvring]of countries and what they do to vulnerable, innocent people”. Contemporary resonances aren’t pat, he suggests, when “you look at people being washed up on the shores of the Mediterranean as a result of what’s going on in Syria … because the innocent victim of all this ends up being this child with learning difficulties”.

Verloc, he adds, is “trapped” by “political manipulation” and “his family are sacrificed for it”. But irrespective of state-level machinations, as the father of a child with learning difficulties, he reiterates that the tragedy is ultimately Stevie’s and Winnie’s.

“That emotional kind of thing is heartbreaking … if you adapt something, you’re always looking for what’s personal in it for you. And your reaction to what’s in books is always first and foremost personal, rather than a literary reaction.”

• The Secret Agent begins on 17 July on BBC1, 9pm