During a visit to an archaelogy dig in the Middle East, Poirot is faced with investigating the murder of Louise Leidner, the wife of famous archaelogist Dr. Eric Leidner.
Many years ago, she had been married to Frederick Bosner, a covert spy, who died tragically in a train accident. After his death, she began receiving death threats (allegedly from her former husband) warning her not to remarry. However the letters had abruptly stopped when she married Dr. Leidner. But, sometime before her death, she had received another letter and had begun seeing visions of a face in her bedroom window at night. Poirot soon suspects that someone at the dig knows of Mrs. Leidner's past marriage and is possibly related to her late husband...
Other characters include fellow archaelogists Richard Carey, who hated Mrs. Leidner; Miss Anne Johnson, devoted friend of Dr. Leidner; David Emmott, a young professional; and Joseph Mercado, a nervous and timid man. Besides these, there's Mrs. Mercado, who also disliked Louise Leidner; nurse Amy Leatheran, who came to treat the victim of her increasing nerves; Bill Coleman, an expert on ancient objects; Carl Reiter, the dig's photographer; Father Lavigny, an expert of old languages; and Dr. Giles Reilly and his daughter Sheila, two local residents.
The novel was adapted into an episode of series eight in the ITV series Poirot. Tropes unique to this adaptation are listed on the page for the series.
This novel provides examples of:
- Adventurer Archaeologist: Most of the main characters.
- Affably Evil: Dr. Leidner is quite charming, is liked and respected by the members of his party, and is honestly sorry for killing Miss Johnson. However, he was also a convicted spy, and is possibly the biggest male Yandere in Christie fiction, stalking his wife for YEARS, keeping other men away from her until he has a chance to re-woo her instead.
- Antagonist in Mourning: Dr Leidner truly loved his wife, even though he had to murder her for what he saw as straying (he was a German spy in the first World War). While he makes attempts to detract from the investigation, in the end once found out he quietly admits his crime.
- Arc Words: "Murder is a habit."
- Asshole Victim: According to Sheila, Louise really, really had it coming after screwing with so many people for her own amusement.
- Attention Whore: Louise Leidner was this, according to many people.
- Busman's Holiday: As usual, Hercule Poirot gets roped into a murder investigation while he's on vacation.
- Call-Forward: According to the epilogue, Poirot travels home on the Orient Express. Also a Call-Back since Murder in Mesopotamia was published two years later.
- Cassandra Truth: Louise Leidner is in fear of her life from her first husband, but nobody really took it seriously until her murder happened. In fact Poirot at first assumes her murderer is one of the members of the expedition, though he is able to get on the right track at the end.
- Chick Magnet: Richard Carey is considered this. He ends up attracting the wife of his best friend, and he can't resist her either, and he hates himself and Louise for their situation.
- Cruel and Unusual Death: Miss Johnson dies after unwittingly drinking a glass of hydrochloric acid.
- Dead Person Impersonation: Dr. Leidner is really Frederick Bosner.
- Death by Looking Up: Mrs Leidner meets her death by Dr Leidner dropping a quern on her skull just as she looks through her room's window. As the window is how she was killed, Dr Leidner arranges evidence so that no one thinks of the window being used as a means. It works, at first, but Mrs Johnson and eventually Poirot work it out.
- Exact Words: Asked by Dr. Leidner if Poirot has come to any conclusion about the threatening letters, Nurse Leatheran says "He hadn't yesterday." Which is true, but since then he has.
- Extreme Doormat: Carl Reiter. Poirot actually takes a break from his case speech to tell him to handle himself better.
- Faking the Dead: Frederick Bosner assumed a new identity, and did it so well that his own wife didn't figure out that she had married him a second time.
- Gaslighting: Dr Leidner did a bit of this to make people assume his wife made up the threats on her life.
- Happily Married: Dr Leidner and Louise Leidner. Sheila Reilly finds it ironic that while Louise loved seeking attention, her husband was so devoted and willing to give it to her so that they both were on wonderful terms. Somewhat subverted as Leidner has been threatening his wife to keep her in line, and when Louise falls for Richard Carey he decides to kill her.
- He Knows Too Much: Miss Johnson figures out how the murder was committed... unfortunately, the murderer also figures out that she figured it out.
- His Name Is...: Miss Johnson tries to tell Nurse Leatheran how the murder went down, but since she's just drank a glass of hydrochloric acid, all she can manage is to say "The window...".
- Hoist by His Own Petard: If Dr. Leidner hadn't killed Mrs. Johnson, Poirot would never have tracked him down.
- Hypocritical Heartwarming: Dr. Leidner defends his people as being incapable of murder. Of course they didn't kill his wife, because he's the one who did it.
- If I Can't Have You…: The constant threat for Louise is that her supposedly dead husband will kill her for being with another man. It turns out that her husband survived the train crash that supposedly killed him. When he took on the identity of Dr. Leidner, he married Louise (again) and stopped sending the threatening letters. However, when she started an affair with an another man, he decided to carry out his threat, preferring her dead than with someone else.
- Ignored Enamored Underling: Miss Johnson clearly pines for Dr. Leidner. He only has eyes for his wife, and her attraction doesn't stop him from killing her by replacing the water on her nightstand with hydrochloric acid.
- I'll Take That as a Compliment: When Poirot describes how David Emmott has the methodical temperament that would be suitable for a murderer, Emmott wryly (yet sincerely) says "Thank you."
- Impersonation-Exclusive Character: We really never learn anything about Eric Leidner, besides that he was a Swedish archeologist. That's because it's revealed he died decades ago in a train crash, and his identity was stolen by German spy Frederick Bosner. Likewise, we never find out what sort of person Father Lavigny is. All the time in the book, he has been impersonated by a jewel thief, as the real Father Lavigny fell sick and was unable to accompany the expedition at all.
- It's Personal: Poirot suspects the murderer could be a relative of Frederick Bosner, Mrs. Leidner's late first husband.
- Jerkass Has a Point: Sheila Reilly is ready to speak ill of the recently deceased, but only because they’re dead and beyond any damage that slander could do to them, while speaking ill of the living can do more harm and requires more tact.
- Locked Room Mystery: Louise Leidner had locked her bedroom door, its only entrance, before her death, and it was also impossible to get in through the window since it was barred.
- Love Makes You Evil: Dr. Leidner.
- Never One Murder: Towards the end Miss Johnson is murdered, suffering a particularly unpleasant death after she drinks hydrochloric acid, because she has figured out who the killer is.
- Personal Effects Reveal: How Miss Johnson discovers who the murderer is.
- Summation Gathering: Poirot does one in typical style, gathering everyone together in order to tell a long story. Lampshaded by Nurse Leatheran when Capt. Maitland demands that Poirot just say who did it.Nurse Leatheran: But that wasn't the way Hercule Poirot did things. I saw perfectly well that he meant to make a song and dance of it.
- This Cannot Be!: Dr. Leidner cannot believe that anyone in his expedition could have a reason for killing his wife.
- Troll: Dr. Reilly can't resist taking a dig at Nurse Leatheran when she is counted as a suspect. It's in good humor though and he doesn't take it too far.
- Unreliable Narrator: Nurse Leatheran narrates the story, and admits that despite her she is biased strongly towards people she likes (Mrs. Leidner) and against people she dislikes (Sheila Reilly). Subverted though; despite her opinions, she is able to tell her story competently and objectively enough.
- Unwitting Pawn: Nurse Leatheran. Dr Leidner employed her to calm and soothe his wife's fears, but in fact it was to reinforce his alibi for being on the roof at the time he killed his wife.
- Upper-Class Twit: Coleman, who is only at the dig because his rich family needed to find something for him to do. He's an amiable dunce and Nurse Leatheran says he's just like a character out of a P. G. Wodehouse novel. He does indeed come off as Bertie Wooster if Bertie was forced to get a job.Coleman: What I'd like to do is have plenty of money and go in for auto racing.
- The Watson: Nurse Amy Leatheran is the narrator of the story and Poirot's assistant in this case.
- What Happened to the Mouse?:Frederick Bosner's brother is a possible suspect but nothing comes of this due to Frederick himself being the culprit, and it's never revealed if he informed his brother of his survival.
- "Where Are They Now?" Epilogue: The epilogue reveals that Sheila Reilly married David Emmott, Bill Coleman was sent to farm in South Africa and that Nurse Leatheran has never been back to the Middle East.
- Yandere: Dr. Leidner a.k.a. Frederick Bosner is an extreme example, resorting to threatening letters, a Dead Person Impersonation, and even murder to stop his wife from straying.