Emma Nightingale prefers to remain grounded in reality as much as possible. Yet she’s willing to indulge her nine year-old son Rupert’s fascination with trains, as it brings him closer to his father, Gunnar, from whom she is separated. Once a month, Gunnar and Rupert venture out to follow the rails and watch the trains pass. Their trips have been pleasant, if uneventful, until one afternoon Rupert returns in tears. “The train tried to kill us,” he tells her. Rupert’s terror strikes Emma as merely the product of an overactive imagination. After all, his fears could not be based in reality, could they?