"The Shadows" is based in Matthew Pearl’s Boston Globe Magazine article “Into the Shadows.” It tells the story of America’s first undercover officers in Boston. Boston was incorporated as a city in 1826 and two decades later, they had to figure out how to make 30 police officers and 150 patrolmen keep a population of almost 140,000 safe. Mayor Josiah Quincy Jr. was embarrassed when a man called Albert Tirrell, charged with the murder of his prostitute mistress was exonerated. He and the City Council put city marshall Francis Tukey in charge and decided to begin a group of cops who would, as the article explains, focused on “investigating complex cases and infiltrating underworld activities using subterfuge. Deductive reasoning — and the blunter skills of persuasion and coercion — had the potential to impose order on the disorder. Officially christened the Detective Police, Boston’s newest force would soon be known by a more enigmatic name: ‘the shadows.’” The decision changed law enforcement in this country.