The prince of a fictional Middle Eastern country has convinced his British friend Bob Rawlinson to smuggle out some valuable jewels, as his country is on the brink of revolution. But when the prince and Bob are later found dead in a plane crash, the whereabouts of the precious gemstones remain unknown, but as the sister of Rawlinson and her daughter was present in the country, suspicions start to centre on the school where the daughter is enrolled. And when one of the teachers is found shot to death in the gym, things start to heat up...
Well, this is a bit of a hodge-podge, albeit an entertaining one. The first third of the novel reads just like another of Christie's adventure thrillers with valuable jewels, a fictional country in turmoil and secret service agents trying to ascertain the whereabouts of said jewels. Then, by the second third, when the first murder occurs, we move towards a more regular Christie mystery, with Inspector Kelsey of the local police taking charge. Only in the final third does Poirot appear, quickly untangling all the loose ends and tying everything up in a lovely bow.
As a sort of hybrid mystery/thriller, it's lots of fun, but the mystery parts aren't wholly successful. The balance between the three different crime strands - the disappearance of the jewels; the murders; and the kidnapping of a young princess from the school - doesn't work very well. While Christie provides some cluing, it's mainly focused on the whereabouts of the jewels and to some extent on the princess's disappearance. I defy anyone to realise the killer from anything mentioned in the story.
Both Mr. Robinson and Colonel Pikeaway make their first appearance here - they will both appear in coming works, among them the already discussed Postern of Fate, which ties the Poirot and Tommy & Tuppence universes together.
While an entertaining read, this novel cannot be seen as an essential part of Christie's oeuvre. I'll award it 44 out of 100.