As with all of Mourning, the scene of Mannon's death makes use of oppressive foreshadowing. Mannon knows already that he house is not his, his wife not his own, and that she awaits his death for her freedom. In some sense, Mannon's death, and Christine's as well, have already happened. Already, Christine appears at the beginning of the scene as the "ghostly form" who will haunt and Ezra is a voice from the darkness of the grave that, in the following play, will possess his daughter.
The action moves quickly here, the scene tensely propelling us through the confession of Christine's treachery, Ezra's poisoning, and Lavinia's discovery of her mother's murder. Assuming the role of Aeschylus's Clytemnestra, an archetype of female treachery, Christine takes her husband to bed to kill him, making the marital bed the deathbed. As the townsfolk will remark in the following act, loving will have killed Ezra Mannon.
For Ezra and Lavinia, Christine is a mother turned lethal whore, Ezra's insults making manifest the degradation of the love object typical of the Oedipus complex. Note here also the racial fantasy at the heart of this degradation. In giving Ezra her body, Christine makes him a property-owner. This relationship makes their marriage racially charged: Christine becomes the "nigger slave" to the "lustful beast" of her husband. For the guilty Ezra, he would even find "cleaner" sex in a brothel. Christine degrades their marriage by acting as if she were his black whore. Ezra, the great northern general, would of course imagine himself as the polar opposite of the Southern slave owner.
As Christine has planned, the couple's argument precipitates Ezra's heart attack. Responding to her father's cries, Lavinia arrives at the last moment to bear witness to her mother's treachery. Ezra rises, in a sense from beyond the grave, to accuse Christine of murder, his momentary second coming prefiguring his role he assumes as the accusing and judging dead in the following two plays.
As Christine anxiously observes, Lavinia appears on the scene here as the house's sentry. Her role as sentry refers not only to her anxious watch over her father's safety, but her duty as a functionary of the Mannon ancestors. Thus Lavinia will again stand as sentry when presiding over her mother's suicide, crying that she has meted out the ancestors' justice. She also plays in sentry in serving as the guardian of the Mannon crypt, initially bent on preserving the familial secrets and repressing the past and then ultimately, as the last surviving Mannon, living out the family curse.
Lavinia's role as sentry puts her in close dialogue with the dead. As we have seen, all the Mannons speak with their dead, whether through the medium of Ezra's corpse or, more frequently, by addressing the ancestral portraits watching over the house. Lavinia in particular appears in conversation with these spirits. Recall, for example, her touching the painted Ezra's hand in Act II, her embrace of and desperate plea to the corpse here, her numerous commands that her father speak from beyond the grave, and, most chillingly, her ventriloquism of that voice itself that comes in the subsequent play.