The Secret History of Wonder Woman. By Jill Lepore. Knopf; 448 pages; $29.95. Scribe; £20. Buy from Amazon.com, Amazon.co.uk

WONDER WOMAN appeared just as America entered the second world war in December 1941. With her skimpy, star-spangled shorts, red bustier, tiara and kinky, knee-high boots, she was an instant hit. Of the thousands of comic-book characters created in the 1940s only Superman and Batman were more popular. Although her star has since waned, Wonder Woman has never ceased solving crimes and triumphing over baddies.

Now, thanks to a new book by Jill Lepore, her secrets and, more intriguingly, those of her creators, are out—and quite unexpected. “The Secret History of Wonder Woman” is not just her history, but a story of feminism and birth control, with a Bohemian ménage-à-trois at its heart.

Ms Lepore is a Harvard historian and journalist. In 2011 she wrote “Birthright”, an essay for the New Yorker about the early politicisation of contraceptives and abortion. While researching that piece she began unpicking the loose threads at Wonder Woman’s seams.

DC Comics launched Wonder Woman partly in response to a backlash by concerned parents against the violence endemic in comics like Superman, whose origins lay in science fiction, and Batman, which grew out of detective novels. Her creator was an eccentric consulting psychologist, William Moulton Marston. “Not even girls want to be girls,” he wrote in his pitch to DC Comics, “so long as our feminine archetype lacks force, strength, power…Women’s strong qualities have become despised because of their weak ones.” Wonder Woman was to be the magic bullet who, without bullets, would silence comics’ critics and, as Marston put it in 1945, act as “psychological propaganda for the new type of woman who, I believe, should rule the world.”

Marston (who wrote as Charles Moulton) became a staunch feminist while at Harvard. The Men’s League for Woman’s Suffrage had just been formed. Florence Kelley, a minimum-wage campaigner, and Emmeline Pankhurst, with her militant brand of universal suffrage—“Deeds, not words”—were beginning to influence American suffragists. They came to speak to the students.

Marston married a fellow feminist, Sadie Holloway. (When she told her father she wanted to go to university, he said: “As long as I am able to keep you in gingham aprons I think you should be content to stay at home with your Mother”. She studied law at Boston University, one of three women in her class.) The marriage ended only with Marston’s death from cancer in 1947, but decades earlier he had fallen in love with Olive Byrne, the niece of Margaret Sanger, a birth-control campaigner. Holloway was given a choice: accept Byrne into her home and marriage or Marston would leave her. The family raised four children; Marston and Holloway told people Byrne was the live-in governess.

Marston clearly believed in women’s rights—when Wonder Woman got her own stand-alone magazine it included a pull-out section with biographies of exceptional women such as Susan B. Anthony and Florence Nightingale. But his was an unusual brand of feminism. “Hardly a page”, Ms Lepore writes, “lacked a scene of bondage. In episode after episode, Wonder Woman is chained, bound, gagged, lassoed, tied, fettered and manacled.” Suddenly she began to appear a little less family friendly. Complaints were made, but Marston was resolute. “The secret of woman’s allure”, he apparently told Gaines, his boss, is that “women enjoy submission—being bound.” It will be interesting to see how DC Comics will handle such sentiments in the new Wonder Woman films they recently announced.