Mary Louise Kelly is a co-host of NPR’s “All Things Considered” and previously served as NPR’s national security correspondent. Her latest novel is “The Bullet.”

In December 1940, the operations chief of France’s largest spy network walked into a bar in the port city of Marseille to recruit a source. The potential recruit was named Gabriel Rivière. He was a burly, mustachioed man who knew more about maritime traffic in the Mediterranean than anyone in town, and as he stared at the spymaster, his jaw hit the floor.

“Good God!” he shouted. “It’s a woman!”

Indeed. To be specific, it was Marie-Madeleine Fourcade, married, mother of two, slender, blond and barely in her 30s. In fairness, Fourcade herself in those early days harbored doubts as to whether she could pull off the gig. In “Madame Fourcade’s Secret War,” Lynne Olson writes of how Fourcade would lie awake after working 16-hour days, haunted by how to pay her team, how to keep them safe and, above all, this question: Would they obey a woman?

Yes, they would. Over the course of World War II, Fourcade built a network of agents across occupied France. They collected intelligence on the movements of German U-boats, on supply shipments sailing in and out of key ports, on which of the bridges into Paris were mined. They were frequently captured by Nazis (in Fourcade’s case, twice) and, in some cases, escaped (again, Fourcade’s record: 2-0). Also, she was shrewd about the advantages of low expectations. “Because she was a woman,” Olson writes, she knew she would be underestimated, “a miscalculation on which she was determined to capitalize.”

Not that Fourcade was above hiding her gender when she could get away with it. British intelligence, for example, had no idea they were dealing with a woman until late in the game. MI6 had come to be a key partner of Fourcade’s network, not least because it was paying the bills. (To commemorate the intelligence partnership, the French network was christened “Alliance.”) But the main point of contact on the French side was Alliance’s founder, a former French military officer named Maj. Georges Loustaunau-Lacau. When he was arrested in 1941, London sent a cable expressing condolences and ending with a terse question: “Who is taking over?”

“I AM AS PLANNED,” came Fourcade’s answer. “SURROUNDED BY LOYAL LIEUTENANTS.” Olson notes that MI6 had never been told Fourcade’s real name or gender. “And she, concerned that they would reject her out of hand, had no intention of enlightening them.”

It’s fascinating to consider all this from the vantage point of 2019 and this #MeToo moment. How much has changed? On the one hand: Check out the CIA today, and you’ll find a spy agency led by a female director and a female chief of the clandestine service. In fact, the agency’s main three directorates — operations, analysis, and science and technology — are all run by women. While we’re at it, the CIA’s top lawyer is a woman too. On the other hand: Do we imagine that a modern-day descendant of the mustachioed Gabriel Rivière would have a reaction much different, if a wisp of a young, blond mother strolled into a Marseille bar and started barking orders?

Having moved myself for years in male-dominated national security circles, I’ll offer the observation that one of the best ways to get taken seriously is to put your head down and produce good work. Fourcade appears to have learned the lesson early, and on top of it, she was too damn busy to dwell on gender politics.

There was the time she had to stuff herself inside a Vichy mailbag to get smuggled across the French-Spanish border. There was the time she escaped from jail by stripping to her underwear, clamping her summer dress between her teeth and squeezing between the boards nailed across the window of her cell. At the height of the war, Fourcade was smoking three packs of cigarettes a day, dyeing and redyeing her hair to disguise her appearance, and moving constantly to evade the Gestapo agents pursuing her. Oh, and did we mention the minor matter that she was pregnant? Fourcade delivered her third child in 1943, a detail Olson dismisses as “yet another complication” and that we are assured “did not deflect her from her commitment to Alliance.”

The evolution of Marie-Madeleine Fourcade is, in other words, a hell of a yarn. As Olson asks, “How could one not be fascinated by the story of this cultured young woman from a well-connected family who had dreams of becoming a concert pianist but ended up as arguably the greatest wartime spymaster in Europe?” Well, yes, when you put it that way.

Yet somehow “Madame Fourcade’s Secret War” manages in spots to be a little dull. The writing is clear, detailed and reminiscent of your high school history textbook. As the names and places and dates whizzed past, I was left hungry for a more fully dimensional, complex portrait of the woman behind the tough-cookie persona. It is possible to devote 400 pages to someone and still leave their character feeling underdeveloped.

Some of the minor characters are given short shrift, too. An example: We meet a young dressmaker (code-named Shrimp) who repairs submariners’ life vests at the German base in Saint-Nazaire. Shrimp’s work provides the perfect perch from which to learn which submarines are coming in for repairs and which are churning back out to sea. It’s a fascinating vignette, but we never learn her real name, or what happened to her, or how she wheedled those secrets from Nazi submariners, or how useful her intel proved to Alliance and MI6. More, please.

None of which is to devalue the broader contributions of the author or her subject. In her acknowledgments, Olson reveals that a common thread through her eight books is a focus on “unsung heroes.” And here we arrive at last at a question I’d been pondering since Page 1: Why the heck have we never heard of Fourcade? The only woman to lead a major French resistance network. A woman who in later life was elected to the European Parliament. And who, upon her death in 1989 at the age of 79, became the first woman to be granted a funeral at Les Invalides, the complex in central Paris where Napoleon Bonaparte and other French military heroes are buried.

Olson posits a few possible reasons for Fourcade’s relegation to the footnotes of history. The inescapable one, though, circles back to where we began: her gender. Charles de Gaulle started a list in 1940, the Compagnons de la Libération. It represented the elite whom he deemed heroes in the fight for France’s liberation. “By the end of the war,” writes Olson, “only 1,038 persons were considered worthy of the honor. Of that number, 1,032 were men.”

Three Alliance members made the cut. Fourcade — the undisputed leader of the network from 1941 through 1945 — did not. Brava to Lynne Olson for a biography that should challenge any outdated assumptions about who deserves to be called a hero.

Madame Fourcade's Secret War

The Daring Young Woman Who Led France's Largest Spy Network Against Hitler

By Lynne Olson

Random House. 428 pp. $30