Middle sister is Milkman’s main character and its narrator. She is 18 at the time the novel’s events unfold, and lives with her mother and three younger sisters in a Catholic district of an unnamed city in Northern Ireland. Her father, Pa, died several years earlier, and her other siblings—three older sisters and four brothers—are either married, dead, or on the run from the Northern Irish authorities. Middle sister herself does her best to stay out of politics; like the majority of people in the district, she is peripherally aware of and sympathetic to the separatist cause, but generally tries to keep a low profile and simply go about her own business. She is intelligent and perceptive, reading novels in her spare time and attending French classes at an adult education center.

Middle sister’s primary strategy for dealing with life in what amounts to a war zone is avoidance. As much as she can, she tries to remain (or pretend to remain) ignorant of what is happening around her—a practice encapsulated in her habit of reading 18th and 19th-century novels while walking violent, 20th-century streets. In many ways, the society around her encourages this approach; the circuitous way in which middle sister narrates her story reflects the euphemisms, double-speak, and half-knowledge that characterize a community under siege.