In the prologue to Triangle, Author David Von Drehle introduces the Triangle Shirtwaist Factory fire and the plight of relatives of the dead who attempted to identify the bodies after the disaster. Many of the victims were badly burned, which made identification a difficult task. Von Drehle recounts the story of Dominic Leone, who lost two cousins and a niece in the fire. Although one was easily identifiable, the other two girls were badly burned, and Leone and his aunt, Rose Colletti, were forced to guess which bodies belonged to their relatives. Although Colletti was initially convinced they had identified one of her daughters, she lost her certainty that night and informed the morgue the next morning. The body was recalled and returned to the line of unidentified dead along the Manhattan pier dubbed "Misery Lane."

In the early twentieth century, workers had virtually no rights, and workplace accidents and deaths were extremely common. Despite this, some factory owners—including Max Blanck and Isaac Harris, the owners of the Triangle Factory—resisted reform and actively bullied striking workers and police to prevent change. The Triangle fire forced New York, and subsequently the nation, to adopt fundamental reforms for workers' rights and safety.