The White Mountains (The Tripods #1)

Young Will Parker and his companions make a perilous journey toward an outpost of freedom where they hope to escape from the ruling Tripods, who capture mature human beings and make them docile, obedient servants.
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This is the first book of the original Tripods trilogy written under the name John Christopher. These young adult science fiction stories are set on Earth ruled by the alien Tripods. A prequel detailing the conquest was added 20 years later.

*John Christopher is a pseudonym of Sam Youd.*

The series:
0.5 (Prequel) When the Tripods Came (1988)
1. The White Mountains (1967)
2. The City of Gold and Lead (1967)
3. The Pool of Fire (1968)

ISBN: 9780745110431