Telephone Time - Season 3 Episode 1 Revenge

A school teacher from Massachusetts comes to a small western town to marry a young homesteader, but finds that he's been murdered. The jury frees the murderer on a phony plea of self-defense. Determined to see justice done, she decides to stay in town as a constant irritant to the murderer's conscience. She makes him so crazy, he picks a fight with one of his friends and is killed. Dismayed by her own vengefulness, the teacher decides that justice would be better served by true social reform. She campaigns successfully for women to be selected as jurors, which results in the second murderer being convicted and sent to prison.