This was fine. Very Point Crime. I think if not for the (entirely different) film it probably would have been forgotten. The twist was very obvious from the very beginning and I don't usually see stuff like that coming.

There were clearly updates made to the text which did feel clunkily added in. I think I'd definitely recommend reading the original text over this updated version.

The interview with Lois Duncan at the end of the book was probably the best part of the whole thing, and surprisingly touching. Frankly it's totally put me off the film.