In the early 1940s, NYPD Dan Brady, an Irish immigrant who, as a boy in Dublin ran messages for the Sinn Fein, is working on a string of anti-Semitic assaults when he catches a murder case of a Bronx Sunday School teacher by a serial rapist. He soon discovers the rapist's pattern of hitchhiking into and out of the city and pioneers a process of cooperation with the FBI and other police departments to conduct a dragnet from Louisiana to New England.

Danny expands his cooperation with the FBI to include the anti-Semitic crimes, particularly burglaries, which he suspects are part of a larger effort to disrupt the war effort. The police commissioner authorizes him to coordinate the investigations of all such suspicious crimes in the city, and when a high school chemistry lab is burglarized of ingredients for high explosives, he realizes he is looking for a ring of potential saboteurs. When the FBI reports Nazi agents having landed on Eastern Long Island, Danny finds himself in a race against time to prevent a major bomb attack.

Based on true events.