This is one of my favourite novels - and I don't say that lightly.
Gripping, clever, mysterious, involving, taut, fast-paced...
In fact a jolly good read!
And speaking as a novelist, I can say it's a great piece of writing, too. Great plot, good characters.
Why is someone doing this to his dear little family? That's the plot. And answering that question is what it's all about.