I've just realised why this book is different, and why it hasn't been done on tv or film very often: there's nobody sympathetic in it. You can't have a love interest between two heartless murderers. Cards on the Table was different. There were human foibles,so it seemed, not this out and out bad.
I agree with you. In fact, nobody shows any sight of remorse. Most of them would do the same thing again.
I have to say that Miss Brent is a really scary woman!
Still, I think it's her best book!