Von Drehle tells the forgotten stories of the victims of the Triangle Factory fire, noting that contemporary newspapers "reported the names of the dead but scarcely anything else about them." He begins with the story of Rosie Freedman, who was eighteen years old at the time of the fire. Freedman had grown up in a predominantly Jewish town in Poland, where Jewish citizens’ freedoms were increasingly restricted after the assassination of Russian Czar Alexander II in 1881. The resulting violence toward Jews, who were blamed for the czar’s death, created waves of emigration to the "goldene medina, or "golden land," of America. Jews who remained were restricted to a region called the "Pale of Settlement," and although emigration was widespread and lasted around a decade, most people tried to continue living in the Pale. Rosie's youth in this region was "shaped by tradition and also by upheaval," as it coincided with an upsurge of Jewish social awareness and self-education. In the early years of the twentieth century, however, the Jewish community in the Pale repeatedly came under violent attack. Pogroms— the violent expulsion of Jews—became increasingly common and brutal; in the 1903 attack on Kishinev, at least forty-five people were murdered by rioters, and hundreds more were wounded. Von Drehle writes,

Some of them had nails driven into their skulls. Others were disemboweled, beheaded, crucified. Children were killed alongside their parents. A baby was used to break windows . . . For nearly two days, the police stood by.

Kishinev was only the "beginning of a reign of terror" that lasted for years. In June 1906, Rosie Freedman's town was attacked. The massacre lasted for three days; by the time it was over, two hundred people had been killed and seven hundred wounded. Rosie’s family decided to send her to New York, where her aunt and uncle lived, and she soon joined the one million immigrants who arrived in the United States in 1907. Rosie and her relatives lived in a tenement building, an example of the popular "dumbbell" design, which allowed developers to reap maximum profits by fitting as many people into a lot as legally possible. Hundreds of tenement fires occurred each year in dumbbell tenements, a result of poor ventilation, overcrowded spaces, and blocked exits.

By the time she was eighteen, Freedman was sending thirty roubles a month to her family back home. Although the East Side, where she lived, was a vibrant place with a large community of fellow European immigrants, Rosie's opportunities for advancement were limited due to her gender. Classes at the Educational Alliance were primarily for boys and young men, and Rosie worked long days in the factory. Despite the popularity of dance halls, to which young people on the East Side flocked on Sundays, "recreation of any kind . . . was an adjunct to Rosie's life," and her waking hours were consumed by her work at the Triangle Factory, where she worked on the ninth floor.

Although around sixty percent of Triangle workers and management were Eastern European Jews, the rest were predominantly Italian. The migration of Italians to America was even larger than that of the Jewish population, with more than two million Italians entering the country between 1900 and 1910. Michela Marciano was from a tiny village called Striano, about six miles from Mount Vesuvius. In 1905 and early 1906, the volcano had been emitting smoke, "but nothing more than they had been accustomed to, off and on, over the centuries." In April 1906, however, "a horrible, dazzling eruption began," the worst in nearly two thousand years, and Striano was covered in ash. Following this destruction, Michela left her parents to sail to New York. Like Rosie Freedman, her options as a woman were limited, and she married in late 1910. Unconventionally for women of her time, and especially women in the Italian community, Michela worked while her husband remained at home, and she even joined the union. Again like Freedman, Michela worked on the ninth floor of the Asch Building.

Von Drehle goes on to explain the layout of the Triangle factory, describing the numerous rows of sewing machines that dominated the eighth and ninth floors. He also describes the different jobs held by the factory workers, including the cutters, who were "confident, swaggering men." Highly skilled, well-paid, and well-treated, they often ignored the no-smoking policy on the factory floor and sometimes threw their cigarette butts into the bins below the cutting tables, which were full of highly flammable scrap material.

At the time of the fire, which occurred on Saturday, March 25th, 1911, the Triangle company was coming to the end of its busy season. It had not been as successful as the owners hoped; fashion editors in Paris and New York had decided the shirtwaist was going out of style, and for manufacturers like Blanck and Harris, "keeping the shirtwaist fresh and popular had become a constant battle." For workers, however, sewing was generally considered a safe occupation, and "the only strains in a garment factory were on the eyes and concentration." On the day of the fire, more than a thousand blouses had been produced, and as the workday drew to a close, employees rushed to finish their work for the day and complete as many garments as possible.

Mary Laventhal, a bookkeeper on the ninth floor, went down to the floor below to retrieve some cuffs just after 4:30 p.m. After heading back upstairs, she distributed pay envelopes with the foreman, Anna Gullo, who rang the closing bell. As workers made their way to the dressing rooms to change before going home for the day, they talked and laughed and sang, until someone noticed the muffled sound of screaming. Smoke could be seen from the windows, and the workers realized the building was on fire.