Claire McCardell forever changed fashion—and most importantly, the lives of women. She shattered cultural norms around women’s clothes, and today much of what we wear traces back to her ingenious, rebellious mind. McCardell invented ballet flats and mix-and-match separates. After World War II, she fought the severe, hyper-feminized silhouette championed by male designers, like Christian Dior. McCardell became, as the young journalist Betty Friedan called her in 1955, “The Gal Who Defied Dior.” Filled with personal drama and industry secrets, this story reveals how Claire McCardell built an empire at a time when women rarely made the upper echelons of business.