While not exactly a “concern”, this book drops you into the middle of a world that is similar to ours, but also much different, which you will want to make sure your child is ready for (for those familiar with the genre, think of a milder dystopian for kids). One character mentions that going down into the pipeworks (under the city) must be like being “buried alive” and this comment could certainly be a scary thought for a child who has probably never thought of this possibility (most of the book doesn’t have anything ‘dark’ feeling like this). They also mention that in the past people have fallen in to the swiftly moving river in the past and were not seen again. In a similar way, the worry throughout the community of the lights that provide all light to the city going out (there is no sun or alternate light) is a somewhat frightening concept to consider (again the author treats this at a good level for the target audience). It is mentioned in passing that one main character has previously lost both parents (dad to sickness, mom while giving birth), which could be frightening. The Grandmother’s mind is really starting to slip and she eventually passes in her sleep (she was the primary caregiver and a kind neighbor steps up to help with the children). There is an example of extreme greed and a shallow friend makes a few unkind comments, calling her boss a “flab face”. This world also has a group called “Believers”. In some ways they remind us of Christians, but the author paints them in an unclear light and does not include them at all in the eventual positive outcome/solution (which feels like a very “modern” view of the world). As a part of the plot the main characters, in an attempt to save everyone, are dishonest about what they are doing and end up breaking into a couple of places they aren’t supposed to be.