The mood of Passing begins with tension, which only increases as the novel progresses. Initially, readers feels a sense of curiosity when Clare returns to Irene's life. This reintroduction creates suspense, as Irene’s response to Clare's reappearance in her life makes readers question what might happen next. The atmosphere is charged with anticipation even when it’s unclear what impact Clare’s presence could have on Irene's carefully structured world.
As the story unfolds, the tension escalates. This is due to Irene's growing jealousy and anxiety and Clare's betrayal of both Irene and—in Irene’s mind—her own Blackness. The reader feels uneasy, which only increases as Brian and Irene’s relationship disintegrates. There’s a constant feeling of impending conflict as Irene narrowly avoids disaster and fends off Clare’s desperate bids for affection and company. Every interaction is fraught with unspoken emotions. Each person is acting like they feel one thing when they are actually feeling another.
By the novel's conclusion, the mood becomes tragic and shocking. Readers bear witness to Clare’s self-imposed entrapment in her marriage and to the devastating outcome of Clare's final act of "passing" between life and death. The inconclusive ending of the novel leaves readers feeling frustrated and mournful, as Clare’s sudden death and Irene’s numbed response seem so anticlimactic.