In the Squalid Mile

This novel, the fourth by Heather O’Neill, opens in 1873, with two young ­aristocrats from Montreal’s Golden Mile, Marie Antoine and Sadie Arnett, playing in “a ­labyrinth constructed out of a rosebush.” The twelve-year-olds stand “back-to-back with pistols pointed up toward their chins.” When a maid dressed only in “drawers” and a “half-undone” chemise races outside to intervene, the pair’s intended game quickly turns to murder, a crime that binds them for life.

Despite their culpability, the friends grow up relatively unscathed from the incident. A decade later, “wild” Marie inherits her father Louis’s sugar factory, which she oversees with ruthless zeal. Meanwhile, “blackhearted” Sadie — after a stint abroad in a boarding school for difficult girls — discovers a love of titillating storytelling and eventually becomes a celebrated writer of pornography.

Such privilege is unknown to those who inhabit the Squalid Mile, O’Neill’s fictitious name for the...