Repressed passions and shameful secrets destroy a New England family.

In New England at the end of the Civil War, the wealthy Mannon family, which made its fortune in shipping, is being torn apart by jealousy and hatred. Just before her father Ezra, a Union general, and brother Orin are due home from the war, Livinia Mannon follows her mother Christine to New York and sees her kissing the much younger Captain Adam Brant in his house. Later, jealous Livinia, who also has been kissed by the sea captain, tells returning officer Peter Niles, her childhood sweetheart, that she cannot marry him because of pressing family problems. She then hints to her mother, whom she has long hated, her knowledge of the affair. After devoted servant Seth Beckwith suggests to Livinia that Adam might be the son of her banished great uncle David and his wife Marie, a former Mannon servant, she questions Adam about his family when he comes calling at the house. Adam freely admits he is a Mannon and tells his cousin that, because of the harsh treatment that his now-deceased mother received from the Mannon men, he pursued Christine to seek revenge on them. Armed with this information, Livinia, who worships her father, confronts Christine about her affair. She is shocked to learn, however, that her mother, who has detested the domineering Ezra since their honeymoon, already knows about Adam's identity and plans to run off with him anyway. As a counter move, Livinia reminds her mother that Ezra will never grant her a divorce and that her age will eventually repulse Adam. Although Christine agrees never to see the captain again, she later reveals to Adam her plan to poison Ezra, who has a weak heart, and become a rich widow. Adam at first balks at participating in the scheme, but is soon goaded into agreeing to it by the hate-filled Christine. That night, Ezra returns home and informs Christine that Orin, whom she loves with the same intensity that she hates Livinia, was wounded in battle, but was made a man by the war. A thoughtful Ezra then tells Christine that the death of war "made him think of life," and that he now wants to start over with their marriage. Although momentarily confused by Ezra's change, Christine finally reveals her affair to him and, when he begins to suffer a heart attack in bed, gives him the poison. The scheme goes awry, however, when Livinia bursts into the bedroom and hears Ezra condemn Christine before dying. Distraught, Christine faints and drops the pills, which the suspicious Livinia then pockets. After Ezra's funeral, the still-recuperating Orin returns home and immediately begins questioning his mother about Adam. Christine reassures her son, who has become embittered by the war, and promises him that they will soon go away together to a "lost island." Christine also tells Orin that Livinia is losing her mind and has been accusing her of outrageous crimes. Consequently, when Livinia tries to convince Orin of Christine's deeds, he demands proof. To satisfy Orin, Livinia takes him to Adam's boat in Boston, and there they spy on their mother and Adam discussing Ezra's murder and their plans to sail away together. Outraged by his mother's betrayal, Orin later shoots and kills Adam at Livinia's request and makes the boat look like the target of robbers. The next day, Orin and Livinia return to the Mannon house and tell Christine what they have done. Overcome with grief, Christine immediately shoots and kills herself. Although Livinia insists to Orin that Adam's murder was justified and saved the family from disgrace, Orin is inconsolable and guilt-ridden. Weeks later, the siblings return home from an exotic island trip and try to resume their lives at the Mannon estate. Orin, who has grown a beard like his father's, cannot let go of his growing guilt, however, and feels uncomfortable in the house. Livinia, on the other hand, has blossomed since her parents' deaths and, while becoming more and more like Christine, eagerly courts the still-devoted Peter. When Orin, whom Livinia is keeping a virtual prisoner at home, realizes that she intends to marry Peter and thereby desert him, he begins writing a confessional "history" of the Mannon family. He then gives the papers to Peter's sister Hazel, who has long loved him, with instructions to read them before Peter's marriage to Livinia. Livinia discovers Hazel with the confession, however, and vows to Orin that she will give up Peter if he will give her the papers. After Orin returns the confession, he tells Hazel he cannot see her anymore and commits suicide. On the day of Orin's funeral, Hazel tells the restless Livinia, who now lingers outside the house, that because of the suspicions surrounding her, Peter has become estranged from his family. Hazel begs Livinia to break off with Peter, but Livinia refuses her request. Later, however, when Peter comes by and bitterly condemns his family and the town, Livinia realizes that the dead have already "come between them." By claiming that she had an affair with an island native, Livinia convinces Peter to end their engagement. Then, accepting that she is forever "bound to the Mannon dead," Livinia orders Seth to nail the shutters shut and remove all the flowers from the house. As Seth begins hammering the shutters, Livinia walks inside her house and forever closes the door on the outside world.