A file of correspondence and memoranda concerning the investigation of the Corby case,in which the defection to Canada of Soviet embassy worker Igor Gouzenko revealed the existence of a Soviet espionage network in Canada. The documents in this file discuss the political fallout of the case in Canada; the discovery of a similar network operating in the United States of America; further investigations into the extent of the Canadian network by police; the first press report of the case, which hastened the Canadian plans for the arrests; the effect of the case on Canadian relations with the Soviet Union; British investigations into a suspect in England; reports on the results of repeated interrogations of the arrested agents; the growing press coverage of the case; a debate over whether the British Official Secrets Act applied to Canada; and the details and jurisdiction of the prosecution.