Sleeping Giants — Sylvain Neuvel

A page-turning debut in the tradition of Michael Crichton, World War Z, and The Martian, Sleeping Giants is a thriller fueled by an earthshaking mystery—and a fight to control a gargantuan power.
 
A girl named Rose is riding her new bike near her home in Deadwood, South Dakota, when she falls through the earth. She wakes up at the bottom of a square hole, its walls glowing with intricate carvings. But the firemen who come to save her peer down upon something even stranger: a little girl in the palm of a giant metal hand.