Private Investigator Paul Whelan works out of Chicago's seamy, gritty Uptown, an immigrant neighborhood full of vagrants, runaways, and, all too often, murder. In Killer on Argyle Street, Whelan is asked by an elderly woman to locate a runaway boy. Mrs. Pritchett had taken the boy in, given him a home, and still cares enough to find his whereabouts. Whelan learns early on that the boy was a runner for a burglary and car-theft ring, and that three former members of the ring have been found murdered in the past month. All the evidence suggests that the boy is dead as well, but Whelan, ever persistent, keeps asking questions, especially when a newspaper account of the murders reveals that one of the dead men is an acquaintance of Whelan's, the younger brother of a childhood friend. Whelan's inquiries bring him to Argyle Street, heart of Chicago's "New Chinatown" and the home of most of the city's Vietnamese community. What he finds along the way leads him deep into a dangerous maze of complicated loyalties, where neither the police nor possible witnesses will cooperate.