Which characters do you particularly admire or dislike? I admire Marc and his sister. Have intense dislike for the kidnappers.
Do you find the characters convincing? The characters are all convincing. Very believable.
How would the book have been different if it had taken place in a different time or place? I think with social media these days, the news of the kidnapping may have had faster response. The warehouse was an eery place that even I would have nightmare about and I wasn't even there.
Disclosure - I received a free copy of the book which did not affect my honest opinion.