an interesting story, but characters little searched

I read this novel in one sitting. The style is fluid, and everything goes faster.
My main regret is the lack of thickness of the characters. It's hard to be concerned about what happens to them.
Apart from that, the story itself is original and exciting. The author does not lack imagination and knows how to conduct his boat.
The end particularly pleased me, and that's what made me decide to have it read to my teenager.
In short, a good read, leaving the reader a little hungry.
The target audience is clearly an adult teenager, my son loved it from start to finish.