Margaret Chase Smith was a woman of firsts: In 1940, she was the first woman by the state of Maine to serve in Congress; nine years later she was the first woman elected the state to the Senate. And in 1950, she became the first senator to stand on the Senate floor and unanimously rebuke Senator Joseph McCarthy of Wisconsin, who rose to power using post-World War II anti-Communist hysteria and the lives ruined of those who him. Margaret Chase Smith's "Declaration of Conscience" speech was a public act of defiance at a time when both Democrats and Republicans were cowed into silence for fear of retribution. It came at a cost: She was shunned by her colleagues, challenged in a primary, and McCarthy threatened to exhibit her personal secrets. Conscience is the story of a remarkable woman who stood up for what was right and refused to back down.