The style of the novel is conversational but also clever and self-aware. For example, in Chapter 2, Dr. Sheppard recounts a conversation in which Miss Russell asked him about cocaine and untraceable poisons:
“Ah!” I said. “You’ve been reading detective stories.”
She admitted that she had.
“The essence of a detective story,” I said, “is to have a rare poison—if possible something from South America, that nobody has ever heard of—something that one obscure tribe of savages use to poison their arrows with. Death is instantaneous, and Western science is powerless to detect it. Is that the kind of thing you mean?”
Much of the book is taken up with dialogue like this, in which the characters speak to each other just as neighbors in a small village would. The sentences are not overly long or complex. Christie uses punctuation and sometimes filler words such as "ah!" to capture the cadence and tone people might actually use in conversation. Christie gives over narration to Dr. Sheppard so that even in moments of description, it is always a character speaking rather than a disembodied author.
At the same time, Christie's lighthearted commentary often comes through her characters. In this exchange, Dr. Sheppard teases Miss Russell about reading too many detective novels. He describes the most exaggerated version of a real trope in detective novels: untraceable poison that comes from someplace a Western nation has colonized but that Western science has never encountered before. Through this meta joke, Christie reveals that she is aware of the conventions and tropes of her genre. She even pokes fun of the way the genre tends to exoticize Western colonies and the way it pushes up against readers' suspension of disbelief. By lightheartedly laughing at her own novel's genre, Christie demonstrates that she is in on the joke and softens the blow of any criticism. It is as if she is telling her readers not to take the book so seriously—it is only meant to entertain, after all.
