A curious young woman probes the perplexing disappearance of the traveling companion who may have never existed in this retelling of the classic suspense story. Privileged Iris Carr is traveling Europe by train when she suffers a fall that leaves her deeply disoriented. After retreating to her carriage, she strikes up a friendly conversation with a grandmotherly Englishwoman named Miss Froy. Before long Iris has fallen asleep, and when she wakes up Miss Foy is nowhere to be found. Upon questioning her fellow passengers about Miss Foy, Iris is deeply disturbed to find they deny any knowledge of her existence. Now, as the train speeds though the European countryside, Iris begins to suspect that she has fallen victim to a sinister conspiracy, and determines to find out exactly who is behind it.