Moving through Car 12, Anna struggles with doubt after Sally Lawrence suggested Seamus might be the killer. She reviews opportunities and motives, noting Seamus had reason to kill Judd and Edith and was never fully searched, though she also recognizes Sally could be deflecting blame. She confronts the timeline around Edith’s death and wonders if Seamus had the chance.

In Car 13, Anna finds Seamus guarding Herb Pulaski’s door. She tells him Sally accused him, then asks directly if he killed Judd or Edith. Seamus appears hurt but firmly denies it, admitting he wanted vengeance but insisting he would not act against Anna’s wishes. Anna believes him and asks for his suspect; Seamus points to Dante, while Anna defends Dante, saying he exposed Kenneth Wentworth’s crimes and is helping them.

Anna withholds Dante’s revelation about her mother’s past with Kenneth. Seamus remains skeptical of Dante, and both express anxiety about surviving the night and about life after their revenge is complete. They reflect on the void that may follow and the likelihood they might not remain connected once their common purpose ends.

The tense quiet breaks when Seamus notices a thin line of blood seeping from under Herb’s door. Anna pounds on the locked door without answer. Seamus runs to get Reggie Davis, who returns and attempts to break in. After initial failed attempts, Seamus and Reggie ram the door together. Dante, Sally, and Jack Lapsford gather in the adjacent doorway, but Anna orders them back.

On the final push, the door frame splinters open. Inside, a dark pool of blood spreads with the train’s motion. The blood trails to a chair by the window where Herb Pulaski sits dead, upright, with a look of terror. His throat has been slit in a curved gash beneath his chin, a markedly more violent killing than Judd’s poisoning or Edith’s smothering. Anna screams at the sight.