Produced by Louis de Rochemont - co-founder/producer of the influential American newsreel The March of Time - this semi-documentary espionage thriller started a trend in postwar Hollywood for true-life crime dramas notable for their realism, "voice of doom" narration and understated use of authentic locations. Readily taking to the documentary style, director Henry Hathaway sets a cracking pace, as double agent William Eythe keeps federal agent Lloyd Nolan informed about the activities of a Nazi spy ring operated from New York by Signe Hasso and Gene Lockhart. The self-congratulatory tone aside, it's enthralling stuff.

The US Government tries to track down embedded Nazi agents in the States.