I’d probably have to say Metro 2033 (the first Book of the series) Mainly because it has such a long and engaging, it does have very few cussing in it but id say it could be challenged Because of the intense details of how they slay the creatures. One of the reasons why flight was challenged because it had vulgure language and it expresses points of a teenager with problems like most the teens today but since their is language and substance abuse id say that’s probably why this book would be challenged. In addition problems that teens today suffer from is most likely substance abuse and depression. What happened to zits was bad because his father left and his mother died and since he thought that if he was violent enough that it could fix his troubles but instead it made him look at a different perspective.