Don't waste your time. The story is completely lacking in originality and plausibility. Even allowing for how long ago it was written, the ignorance of the laws of physics is unforgivable. And the narrator/hero is so dense that I wanted to slap him. Apart from that, it is mostly harmless.
Recent comments: User reviews
The twin sisters have real personalities, unlike many fictional twins, and are very endearing characters.
The ending doesn't quite match up to the rest of the book, therefore only four stars.