John Whiting is part of a Communist espionage ring. He specializes in blackmailing leading executives of defense contractors. Hugh Zimmerman, one of his targets, balks and the two engage in a vicious fight. By accident, Zimmerman falls out of a hotel window to his death. Whiting's superiors pressure him to come up with an alternate way to obtain information on a top secret U.S. project. Erskine and Colby are assigned by the FBI to investigate Zimmerman's death and end the spy ring's activities.
—Bill Koenig