At the start, Anna realizes Seamus Callahan is the murderer, concluding he had the strength, opportunity, and motive to kill Edith Gerhardt, Herb Pulaski, and Judd. When she tries to flee, Seamus restrains her and takes her knife, then seats her in the lounge car rather than attacking her.

They speak candidly. Anna accuses Seamus of discovering Judd’s hiding place and then strangling him; Seamus admits it. He says he wanted vengeance for their murdered brothers and others, and that while Anna wanted the conspirators alive for justice, he wanted them dead. He says he went along with her plan because he loves her, but when an opportunity arose, he killed.

Anna insists they are better than murder, says she will never forgive him, and warns he will be arrested in Chicago. Seamus understands she will tell the truth. He describes the killing as “beautiful” and a “sweetest release,” and reminds her he is already doomed by his illness. He gently pins her father’s silver locomotive pin onto her dress and kisses her cheek.

Seamus then moves forward through multiple cars toward the baggage car. Realizing his intent, Anna pursues him as he opens the side doors to the rushing, snow-whipped landscape above a river and trestle bridge. At the threshold, he says he is leaving.

For a moment, Anna thinks he will step back when he runs to her and embraces her. Instead, Seamus presses a revolver into her hand, telling her she knows what to do and can end this. He breaks away, returns to the open doorway without looking back, and steps off the moving train, disappearing from sight.