This was really fun - the mystery was intriguing, keeping me thinking and guessing, and the kids were interesting, sympathetic characters. They all appear to be tropes at the beginning, but their stories deepen into believable, textured human narratives.

It's Agatha Christie - what more needs to be said?

OK, one thing this reinforced for me is that Christie wrote characters and dryly comedic narration so well, her books are eminently re-readable, even though they're mysteries. That's saying something!