The Train as Sea Voyage (Similie)
Quite early in the novel, before it becomes apparent that this will be no ordinary train journey, Poirot watches the awkward flirtation between Debenham and Arbuthnot and muses to himself that the train is more thrilling than one might imagine. He uses the idea of a journey by ship to make this comparison through simile, thinking “The train, it is as dangerous as a sea voyage!” This turns out to be a clever bit of foreshadowing, since this particular train winds up being full of dangers. The comparison also prompts readers to reimagine the book's setting, rejecting the idea of the train as a place of refuge from the outside world. Just as a ship at sea faces threats from storms and various other outside dangers, so does this train face threats from outside—here in the form not of storms, but of violence and vengeance.
A Caged Wild Animal (Metaphor)
When he encounters Ratchett, Poirot feels an immediate disgust towards him, and uses the metaphorical image of a caged animal to describe his impression of the antagonist. He tells Bouc that "the body—the cage—is everything of the most respectable—but through the bars, the wild animal looks out.” In this metaphor, Ratchett's genteel-looking clothes, body, and manner are represented by a cage, while his amoral, violent personality is represented by an animal. One thing that makes this metaphor interesting is that it flips the power dynamic between Ratchett's external presentation and his real, dangerous ways. A wild animal in a cage is no longer dangerous, since the cage limits its movements and keeps it from harming others. But Ratchett's false gentility is not a restriction imposed on him—rather, it's a facade he uses to reassure others and thereby get away with violence and harm. To extend the metaphor further, he's like a wild animal with a key to his own cage. At this early phase in the book, though, Poirot doesn't realize how powerful and dangerous Ratchett is, and so the metaphor seems sufficient.
Passenger Descriptions (Similes)
If Ratchett is compared to a wild animal, other passengers on the train are compared via simile to tamer and more domestic creatures. Princess Dragomiroff is "toad-like," while Greta Ohlsson has a face "rather like a sheep." Foscarelli, later, is described as having a "cat-like tread." These comparisons all express various physical facts about the passengers—the Princess's age and ugliness, Ohlsson's dutiful attitude, and Foscarelli's irrepressible energy—but they also make the people they describe seem fundamentally harmless. They're not exotic, wild creatures—they're the kind of animals you'd keep in your house or backyard. Of course, that ordinariness cloaks their more sinister activities, but another animal simile hints that the Princess, at least, isn't as domesticated and harmless as she seems: she's later described as having "claw-like" hands.
Poirot's Eyes (Simile)
Yet another animal simile is used to describe Poirot, who is neither as dangerous as a caged animal nor as innocent as a farmyard one. While he's starting to look for evidence, Christie writes, "Poirot's eyes were darting about the compartment. They were bright and sharp like a bird's. One felt that nothing could escape their scrutiny." Here, once again, the comparison isn't just a physical description to portray how Poirot's eyes look—it's a hint at what his personality and role in the book will be. Poirot, like a bird, has an extraordinary ability to rise above his immediate surroundings and see the world from, well, a birds-eye view. He's able to examine how various pieces of his reality fit together, helping him turn disconnected clues into a complete theory of the case before him.
The Disappearing Person (Simile)
Poirot, when trying to imagine where the missing murderer may be hiding, says of the situation, "like the ‘disappearing person’ in the cabinet, it is a trick. It is our business to find out how the trick is done." This is one of several moments in the text where Poirot compares the case and the murder of Ratchett to an elaborate performance, and as a matter of fact, it is. The culprits in this book have made an art form of their crime, bringing a theatrical flair to the roles they play and scripting each moment of the investigation. They even throw in an entire scene—the placement of the scarlet kimono on Poirot's luggage—for no reason other than to entertain him and build suspense. Though Poirot doesn't quite know it when he uses this simile, it's absolutely true that the passengers on the train are behaving like magicians, actors, and entertainers.
Mary Debenham's Face (Simile)
When describing the appearance of a particularly spirited Miss Debenham, the narrator makes use of yet another bit of ship imagery. "The sweep of her hair back from her face, the curve of her nostril suggested the figure-head of a ship plunging gallantly into a rough sea." In this moment, the character's (metaphorical) woodenness—her rigidity and unwillingness to show emotion—is transmuted into literal woodenness. She is no longer a mere human, but instead becomes a larger-than-life, iconic figurehead. The image of her face "plunging gallantly" into dangerous waters suggests that the character is tougher than she seems at first glance. Animated by righteous anger, she becomes a different and more fearsome version of herself.
