I hear this question frequently. I usually recommend the dystopia novels like “City of Ember,” “The Giver,” “Matched,” and such. This week I added “The White Mountains” by John Christopher. Written in the 1960’s, the science fiction setting stars 13 year-old Will Parker. People have been conquered by 3-legged machine-like creatures called Tripods. When a person turns 14 years old they have a Capping ceremony where a mind-control device is implanted directly on the person’s skull. Will learns about what life was like before the Tripods came and decides he does not want to be capped. He makes a run for it it the White Mountains where he has a chance of living a free life. This trilogy was a big hit in the ’60’s- I hear there was a BBC tv show. John Christopher passed away in February. Recommend for ages 9/10 and up.