The White Mountains — John Christopher

Will Parker lives in an enslaved world. Long ago, the Tripods--huge, three-legged -machines--descended upon Earth and took control. Now people unquestioningly accept the Tripods' power. They have no control over their thoughts of their lives.

But for a brief time in each person's life--in childhood--he is not a slave. For Will, his time of freedom is about to end--unless he can escape to the White Mountains, where the possibility of freedom still exists.