They’d almost done it. A group of friends, digging a tunnel from West to East Berlin to rescue dozens of men, women, and children. Above their heads, the Berlin Wall: 27 miles of concrete, fortified with metal shards, trip wires, and thousands of border guards armed with Kalashnikovs.

The group—German students—had been separated from friends, family, and lovers for months, ever since August 13, 1961, when the barbed wire dividing East and West Berlin suddenly appeared. Now, after weeks of digging the escape tunnel, the students had run out of money. Without cash for equipment and food, it was looking like they’d have to abandon their plan.

Over the past three years I’ve been interviewing those diggers, discovering the story behind the most remarkable escape under the Berlin Wall for my BBC podcast and, now, my book, Tunnel 29. Over apple cake and pretzels, these men—now in their 80s—told me about the leaks, the electric shocks, and the Stasi spy who betrayed them.

What I wasn’t expecting was the final twist in the story: the man who came to their rescue at their moment of financial crisis.

The Right Place at the Right Time

Around the time the students were considering ditching the tunnel, halfway across the world, a hotshot New York City television executive at NBC News was obsessing over an idea. Reuven Frank had in mind a documentary he hoped might win the ratings battle between NBC and its arch-rival, CBS.

NBC’s Reuven Frank, whose search for a Cold War escape story collided with a group of German tunnel diggers in desperate need of funds.

Frank had been in Berlin when the East German government constructed the barbed-wire barrier that preceded the Wall. He was in the right place at the right time, and ensured that NBC was the first American news agency to break the story, filing footage of East German soldiers pummeling concrete posts into the ground.

That day, as Frank watched Berliners wave to each other over the barbed wire, he had one question: How could he capture the drama of what was happening, the desperation of those in front of him? That’s when the idea struck him. What if he could find someone plotting an escape? NBC could film the operation as it happened, every twist and turn.

Ahead of his time, Frank understood that if news journalists borrowed from the worlds of drama and film, they could move people, not just impart information. (Frank also understood that this would help their ratings.) If NBC were to find and film an escape from the East, then America could see firsthand the human drama unfolding in Berlin, a city that had become the flash point in the new Cold War.

What if he could find someone plotting an escape?

The day the barbed-wire barrier went up, Frank set his Berlin correspondent, the charismatic Piers Anderton, the task of finding an escape story. For months, Anderton searched and found nothing. Then, one day, a friend tipped him off to a group of students with an improbable, perilous mission to dig a tunnel from West to East Berlin—a mission that had been stalled due to lack of funds.

NBC correspondent Piers Anderton, left, and cameraman Peter Dehmel, right, with West Berlin student and tunnel digger Domenico Sesta.

Anderton immediately flew back to New York to tell Frank, and at NBC headquarters the two men concocted one of the most controversial deals in TV-news history: they would give the students money for equipment, and, in return, the diggers would let them film everything.

Over the next four months, two NBC cameramen lay inside the tunnel that originated in the cellar of a cocktail-straw factory in Bernauer Strasse, in West Berlin, filming the digging as the tunnelers inched toward East Berlin. They filmed a glamorous red-haired messenger as she risked her life delivering missives to would-be escapees in East Berlin, and captured 29 East Berliners crawling into the other half of their home city, one that now resembled a different country.

The events that NBC filmed were extraordinary, so unparalleled, that Frank flew to Berlin to personally shepherd the footage back to New York.

After weeks editing the film, there came an unexpected hitch: worried that the documentary might exacerbate tensions with the Soviet Union, John F. Kennedy’s White House tried to ban it. But NBC pushed back, and eventually, at 8.30 P.M. on a frosty December evening in 1962, Americans in 18 million homes watched The Tunnel.

The response was unlike anything Frank had dared imagine. The Boston Globe wrote that the film was “probably without parallel in the brief history of television.” The documentary won three Emmys, and the United States Information Agency bought hundreds of copies and screened them all over the world (including in West Berlin).

There were even rumors that Kennedy watched it and was moved to tears.

Helena Merriman’s Tunnel 29: The True Story of an Extraordinary Escape Beneath the Berlin Wall will publish on August 24 from PublicAffairs