I Was a Communist for the FBI is a 1951 American film noir drama directed by Gordon Douglas, and featuring Frank Lovejoy, Dorothy Hart, Philip Carey, and James Millican.
Matt Cvetic Frank Lovejoy, who works in a Pittsburgh steel mill, has been infiltrating the Communist Party for the FBI in Pittsburgh for nine years. During this time he has been unable to tell his family about his dual role, so they believe he is a Communist and despise him.He becomes emotionally involved with a Communist school teacher Dorothy Hart, who is becoming disenchanted with the party. She breaks with the party when it foments a violent strike. Cvetic helps her escape the Communists in violent sequences in which two Communists and an FBI agent are killed. ........
Source: Wikipedia