From the very first sentence, there are mysteries for the reader.  Who is Jonas?  Why is he frightened?  That is always a good way to gain a reader's interest!  As the first chapter continues, we can see there is a community.  We have to wonder what kind of community it might be.  We see it's a community that doesn't allow planes to fly overhead.  That is unusual, isn't it? We know this is a world in which there are airplanes, though, so the setting of the story cannot be in the distant past, and is likely to be at least in the present, or perhaps the future.  As we continue to read, we see many unusual responses from the people in the community and unusual rituals, for example, that they have to drop everything and hide when a plane flies overhead, that people might be "released," that feelings must be discussed with one's parents at dinner, that everyone is permitted to have two children, one male and one female.  The world into which the reader is drawn has enough similarities to not be completely alien, but is unusual and mysterious enough for the reader to want to keep reading and solve the mysteries.