In Agent Josephine (PublicAffairs, July), Lewis uncovers the WWII espionage career of Josephine Baker.

What drew you to this story?

Josephine Baker is an enigma. I was drawn in by the question of how a superstar, a very, very distinctive, international entertainer, the most photographed woman in the world by the late 1920s, could take on the role of a spy. How could she, with so many strikes against her—Black, a woman, married to a Jew, already identified and targeted by the Nazis—take these risks? How could she stand firm with the Allies when so many others had lost heart? How could she be so sure that America would enter the war—and win?

What do people who think of Josephine Baker mainly as a scantily clad cabaret performer get wrong about her?

The lady in the banana skirt, she is not. Agent Josephine is the veritable, true Josephine. Beneath her public persona is a woman committed to the struggle against evil. She was a beacon of hope, an inspiration, absolutely unbreakable in terms of spirit and morale. She was a survivor: her childhood in poverty amid racism in St. Louis, Mo., was crucial. Having been forged in that fire gave her an edge.

Why did you include the stories of so many other WWII spies?

To tell Josephine Baker’s story, I had to tell the stories of her fellow special agents: Wilfred Dunderdale, the model for James Bond; Col. Paul Paillole, her chief at the Deuxième Bureau; Jacques Abtey, her recruiter, handler, and lover; and the former German national Hans Müssig. These people were more experienced, more qualified than she, but each of them expressed appreciation for Baker’s spycraft. I had never heard of them, and very little has been written about them or by them.

Baker’s war is a detective story, written in layers. Her own words suggest she is not telling everything. She died around the time when the 30-year restriction on war secrets lifted. She never spoke of her work. She was traumatized, certainly by her visit to Buchenwald. She stepped forward to do that when asked, but she never spoke about it. As a war reporter, I know that silence—I never again wanted to step into the darkness I witnessed.

What are the lessons of Josephine Baker’s life story?

When all looked lost, when she could so easily have run—an American star fleeing to her homeland for safety—she chose to stay. She chose to stand and to fight for freedom and justice against Nazi hatred and bile. Stories like Josephine’s are essential. We have to keep hearing them. We can never afford to take our freedoms for granted—freedom of speech, freedom of the press, et cetera. I say this from my heart: freedom has to be fought for every day.