Among the fabled tycoons of the Gilded Age—Carnegie, Rockefeller, Vanderbilt—is a forgotten figure: Mrs. Frank Leslie. For 20 years she ran the country’s largest publishing company, Frank Leslie Publishing, which chronicled postbellum America in dozens of weeklies and monthlies. A pioneer in an all-male industry, she made a fortune and became a national celebrity and tastemaker in the process. But Miriam Leslie was also a byword for scandal: She flouted feminine convention, took lovers, married four times, and harbored unsavory secrets that she concealed through a skein of lies and multiple personas. Both during and after her lifetime, glimpses of the truth emerged, including an illegitimate birth and a checkered youth.