Christopher’s real name was Sam Youd, and he wrote under several other pseudonyms as well-Hilary Ford, Peter Graaf, Stanley Winchester-ultimately publishing more than fifty novels in all. “ The White Mountains” is the first volume in the Tripods Trilogy, by the British author John Christopher, who died in 2012. “And I knew that I would rather die than wear a Cap.” “I could not stay, any more than a sheep could walk through a slaughterhouse door once it knew what lay beyond,” he tells us.

He has adventures on the high seas and amid once great but now abandoned cities, finally finding his way to a small group of free humans working to launch a resistance. Then a young hero named Will, through a great deal of luck combined with an innate skepticism, figures out what’s coming and flees before being capped. When the adolescents are returned to the outside, they have mind-control devices woven into their scalps, robbing them of free will-depriving them, more specifically, of any desire to fight the creatures that manipulate the machines.

Humans attend “capping” ceremonies around the time of their fifteenth birthdays, in which long mechanical tentacles swoop down from the Tripods to yank eager teens skyward, one by one, into their interiors. Towering, inscrutable machines called Tripods stride about like giant Humvees atop metal stilts. “The White Mountains,” a young-adult novel first published fifty years ago, is set in the future, at a time when the Earth has been rendered entirely rural and has been taken over by aliens.

Maria doria russell the sparrow