RUTHFULLY YOURS

The only challenge was getting in touch with him.

Armed with a seemingly limitless budget, the KGB had put an estimated 50,000 spies on the streets of Moscow, wrapping the city in an impenetrable surveillance blanket. Any CIA officer who left the U.S. embassy would be followed by highly-trained teams of 20 or more.

So many CIA assets had been exposed and killed over the last decade that the station had all but stopped trying to arrange face-to-face meetings. Some spymasters in Washington viewed Moscow as a lost cause. The station chiefs had only one card left to play.

When he arrived in Moscow in 1976, Tony Mendez had spent 11 years at the CIA but had little experience in covert operations. He’d originally been recruited as an artist. Now he ran the agency’s disguise branch.

Mr. Mendez met with every field officer in Moscow. He logged their exact clothing and shoe sizes, collected hair samples and color-matched their skin tones. A few months later, he returned from his laboratory with some unusual cargo: enough masks, wigs, dental facades, prosthetics, makeup palettes and made-to-measure costumes to put on a magic show. If the CIA wanted to operate freely in Moscow, its agents had to disappear.

Mr. Mendez and his team trained operatives to apply disguises in layers and showed them how to radically alter their appearance on the street, changing from a man in a suit to an old woman in a shawl in less than 45 seconds. To help them bail out of moving cars undetected, CIA technologists invented the “Jack in the Box,” a briefcase containing a spring-loaded inflatable dummy that popped up in the empty seat.

As far-fetched as it sounds, this experiment in deception and illusion became the central pillar of a unique operational mindset known as “the Moscow Rules.” By learning to outfox the KGB, the Moscow station not only connected with TRIGON, it scored some the biggest espionage coups in American history.

Last Saturday, at the age of 78, Mr. Mendez lost his battle with Parkinson’s disease. While tributes have hailed him as one of America’s greatest spies, the full story hasn’t been reported. These details about his work in Moscow, which were recently declassified, came from the draft of a forthcoming book.

The operation Mr. Mendez is best known for was the hair-raising exfiltration of six U.S. diplomats from Iran in 1980. After concocting a madcap cover story about a fake Hollywood movie, he posed as an Irish filmmaker and smuggled the diplomats out of Tehran disguised as a Canadian film crew.

This audacious feat of leadership earned Mr. Mendez the Intelligence Star for valor, but like all CIA operations, its details were immediately locked in a vault. When Mr. Mendez retired in 1990, he never imagined the story, or his identity, might be disclosed.

In 1997, however, the CIA’s then-director, George Tenet, decided to declassify the operation. He even told Mr. Mendez to talk to the press. The story would inspire the 2012 movie “Argo,” in which Ben Affleck played Tony. It won three Academy Awards including best picture.

Mr. Mendez was a reluctant celebrity. He felt more comfortable blending into the background. But he also realized that his unsolicited fame could be used for good. Together with his wife, Jonna, herself a former CIA chief of disguise, he won the CIA’s approval to write books.

And that’s how I got to know them.

In 2002, I arrived at a Manhattan restaurant fully expecting to be dazzled. My wife, Christy Fletcher, a literary agent, had invited me to meet two of her newest clients—Tony and Jonna Mendez.

Tony wasn’t just a spy, he’d been named one of the 50 most-influential “Trailblazers” in CIA history. I pictured him arriving in a Savile Row suit with a shoulder holster, arm in arm with Jonna in diamonds, black Chanel and a dagger strapped to her thigh.

I realized I had a lot to learn about spies.

As their books make clear, the best cover for a real spy is to be neither remarkable nor unremarkable. Tony came to dinner wearing jeans and a sweater. He was handsome, but not in a way that turns heads. No matter the topic, he spoke in the same low, colorless rumble. The Mendezes were warm, curious and unfailingly modest. When it came to the CIA, they mostly talked about lifelong friends they’d made in the field.

Tony and Jonna didn’t think they should receive all the credit. Becoming authors was a way for them to acknowledge the artisans, tradesmen, magicians, makeup artists and Hollywood prop-masters who had made invaluable contributions by sharing their trade secrets.

They also wanted Americans to know that CIA officers weren’t deranged assassins, but good, hardworking people trying to keep the country safe without expecting to be thanked.

One of the oldest leadership paradoxes is that we seldom get to know the truly great ones because they do not care to be seen. One of the most important sacrifices Tony Mendez made for his country was coming out of retirement for one last operation: letting the world in.

What Mr. Mendez taught me about leadership is that no matter what kind of work you do, your fate always depends on collaboration. Spying is perceived as a lonely, isolated job for robotic James Bonds who trust nobody. In reality, espionage is the ultimate team sport.

As Jonna recalls, Tony once convinced a group of CIA technical staffers to spend many unpaid nights running around the streets of Washington. They were helping him train future Moscow operatives by mimicking the surveillance tactics of the KGB.

A leader’s foremost job is making other people better. In Tony’s case, however, that often meant persuading them to risk their lives doing something outwardly ridiculous. To pull it off, he showed people that he cared, that he’d put the work in and that he’d be right beside them. He never projected anything but unflappable calm.

The last book Tony and Jonna co-wrote, “The Moscow Rules,” is due out in May. Today, as Russian spies again stand accused of trying to subvert American democracy, Jonna hopes the book will draw useful parallels between our present predicament and the intelligence challenges of the Cold War.

Above all, it will finally tell the story of Tony Mendez in full. He was a spy but he did not traffic in ruthlessness. His tactic for defeating an authoritarian enemy was something I’d describe as weaponized mischief. Ask him a question he wasn’t authorized to answer and he wouldn’t say a word. His eyes always responded, though. They would literally twinkle.

One particularly puckish scheme his team devised was “lying doggo.” That’s when an operative departed the embassy disguised as an Afghan hound. “If you have a good wigmaker, you can do anything,” Jonna says.

In the end, bullets didn’t win the Cold War. Disguises did.