It is late afternoon in front of the Mannon house. The house is in the style of a Greek temple style, featuring a white, columned portico that stands like an "incongruous white mask." From the town, a band is heard playing "John Brown's Body." From the rear, the gardener Seth Beckwith is heard singing "Shenandoah" in the wraith of a baritone. Amos Ames, a garrulous and gossipy carpenter, his wife Louisa, and her cousin Minnie follow. They have come to spy on the Mannons.
Seth proclaims that if the news of Ezra Mannon's return is true, they will all be celebrating tonight. He praises Mannon as uniquely able, having taken over the shipping business upon his father Abe's death and become a judge, a mayor, and then brigadier-general for the Union. Louisa remarks that while the town may be proud of Ezra, it has little love for his "furrin lookin' and queer" wife Christine.
Changing the subject, Seth goes off to meet Mannon's daughter, Lavinia. Suddenly Christine appears and the trespassers hide. Christine is a distinctly handsome woman of copper and bronze hair: her face gives the impression of a "wonderfully life-like pale mask." She pauses and listens to the distant music defensively and then passes without having noticed the trio. Ames remarks upon how like all Mannons, Christine is "secret lookin'." Louisa urges him to tell Minnie about one of the Mannon's most scandalous secrets, the story of Abe Mannon's brother David marrying that "French Canuck nurse girl" he got pregnant.
Seth returns and then Lavinia appears. She looks strikingly like her mother, bearing the same mask-like countenance, but does all she can to emphasize their difference. Dressed in somber black, Lavinia moves in a wooden, square- shouldered, and militaristic manner. She pauses to listen to the music with vindictive satisfaction.
Seth tells her that the war is certainly over and her father coming home. He asks where she was last night, forcing her to admit, as if admitting a secret understanding between them, that she was in New York. Immediately, however, Lavinia stiffens, claiming to not know what Seth is talking about. He concedes but wonders if he should warn her against Captain Brant.
Before Seth can continue, however, Lavinia's guileless childhood friends, Peter and Hazel, arrive. Hazel worries if Lavinia's brother and her would-be sweetheart, Orin, has been wounded. Impulsively she takes off, teasingly ordering Lavinia to treat her brother kindly.