In ‘A Spy Among Friends,’ B.F.F. Betrayal at an International Level

“Why wasn’t he in custody?” asks the MI5 officer Lily Thomas. It is January 1963, and Thomas is talking about Kim Philby, a British intelligence agent who, after being exposed as a Soviet spy, has escaped to Moscow. Nicholas Elliott, Philby’s closest friend and a fellow member of the foreign intelligence agency MI6, looks slightly nonplused. “Well, that’s not how we —” he begins, before coming to an abrupt halt.

That “we” is at the heart of “A Spy Among Friends,” a six-part series based on the book of the same name by Ben Macintyre, and starring Guy Pearce as Philby, Damian Lewis as Elliott and Anna Maxwell Martin as Thomas. The series, produced by Sony Pictures Television, premieres March 12 on MGM+.

It’s the “we” of the old boys’ club, of men bonded by private schools, an Oxbridge education, members-only clubs and the confident assumption of their right to power. The show explores the psychological shock of the realization that a figure considered “one of us” was something quite different all along.

“MI6 tended to attract those public schoolboys, people who had no hesitation about bending the rules because they thought they were above the rules,” Macintyre said in a recent interview. “They believed they were born to lead, and they couldn’t imagine that one of their own could be a traitor.”

The TV adaptation was written by Alex Cary (“Homeland”) and directed by Nick Murphy (“Blood”). Like the book, it is both a tale of espionage and the story of a friendship and a betrayal that is as personally devastating for Elliott as the political betrayal is for the Western powers.

Philby’s story is true: He was one of the Cambridge Five, a group of upper-class Englishmen recruited by the Soviets while in college, and who were eventually, and gradually, unmasked following World War II, after they had been working for the Communist cause from inside British intelligence services for decades.

“It’s such a well-known story in the U.K., Philby as the most successful traitor of the 20th century,” Lewis said in a video interview from New York. “This is a sneak peek at a more psychological, emotional way of looking at it.”

Philby was both Elliott’s best friend and his idol, Lewis said, and Elliott “fatally continued to facilitate his treachery.” Lewis added: “The great tragedy is that he realizes in retrospect that the man he loved and enabled and defended had gotten thousands of people killed.”

Macintyre said that he learned about the Philby-Elliott friendship from the novelist John le Carré, who described it to him as “the best unwritten story of the Cold War.” When he began his research, he discovered “comrades in arms who loved each other as much as heterosexual men in Britain could.”

“It’s a very intimate treachery,” Macintyre said.

The book, full of biographical detail and historical context, wasn’t easy to adapt, Cary said in an interview, adding that Lewis, whom he had worked with on “Homeland,” helped him develop the script and the show’s approach.

“We had long, long conversations about the balance between spy-narrative red meat and a story about friendship,” Cary said.

He came up with the fictional Thomas, he said, as “a device through which we could engage with Elliott emotionally,” and as an acknowledgment of the various women in Macintyre’s book who are “involved in an unsung way.” He added that he knew introducing a central female character to the story could “be called woke, which is fine with me!”

Thomas, with her northern accent and blunt manners, embodies the class differences between MI5 (which investigates matters of national security, like the F.B.I.) and MI6 (the foreign intelligence service, like the C.I.A.). But her character also suggests a redemptive path for Elliott, who gradually becomes aware of her qualities and potential.

“She represents what has to change in British society, but also has to play as a real person,” Maxwell Martin said in an interview. Thomas is there, she said, “to serve a narrative — someone who will cleave open Elliott’s mind and his subtleties, his emotional brain and his heartbreak, and someone who would challenge what happened in Beirut.”

Beirut, where both men had been stationed, is where the final confrontation between Elliott and Philby takes place. Cary uses their long, elliptical conversation as a central structuring device for the show, which moves swiftly and without any identification between countries, eras and story lines. “That allowed me to tip my hat to the le Carré ‘Tinker, Tailor’ genre,” Cary said.

Anchoring the rapidly shifting scenes are conversations: between Philby and Elliott, between Thomas and Elliot, and between Philby and his Russian debriefer. And between these, there are subplots: a fictional one involving a C.I.A. plot in Moscow after Philby’s defection, a true one about the identification of Anthony Blunt, the curator of Queen Elizabeth II’s art collection, as another member of the Cambridge group.

“A key decision a director must make is the relationship between your camera and the story,” said Murphy, the show’s director, discussing the story’s shifts in time and location. In the show, “the camera reacts to everything, it doesn’t anticipate, which allows the audience to discover everything as the characters do.”

Murphy’s London is a gray, monochrome place, full of brown-suited men and women who are constantly lighting cigarettes in dim rooms. “The era is often delivered cinematically as a tribute to the swinging ’60s,” Murphy said. “But the ’60s hadn’t swung yet; it was an England and a Europe trying to get off its knees after the war.”

The Moscow that Philby escapes to is an even more drab city of slushy snow, long lines and drunks on the street. And although he is nominally welcomed as a hero, the K.G.B. is deeply suspicious that he has come to Moscow to spy for Britain.

Pearce said that Philby mostly remained an enigma to him, too: “Did he really want to go to Moscow, or take the offer that Elliott makes of a peaceful life in the country in return for a full confession? Would his ego have allowed him to become an ordinary person in England?”

While Philby’s flight to Moscow, and whether Elliott was complicit in it, remain an important ambiguity, the central question of the show, Cary said, is “whether there was sincerity in the depths of that friendship, even as there was duplicity in the great arc of the friendship.”

That is also the essential question for Elliott, played by Lewis with a fine-tuned opacity that occasionally cracks to reveal the pain beneath.

“It is like a love story,” Lewis said. “He feels like the cuckold who gave everything blindly to the relationship without knowing he has been cheated on.”

Midway through the first episode of the series, Murphy recreates the televised news conference that Philby gave after he was accused of being the “third man” in a Communist spy ring that included his fellow Cambridge student Guy Burgess. Asked whether he still regarded Burgess as a friend, Philby hesitates, then gives an answer that is perhaps the one sincere sentiment he expresses in the show:

“On the subject of friendship,” he says slowly, “I’d prefer to say as little as possible, because it’s very complicated.”