The Themis Files

Sylvain Neuvel's Themis Files opens when a girl falls into a hole in South Dakota and lands on the palm of a giant metal hand buried underground; the trilogy picks up years later as she leads the team trying to determine what the hand is part of and why it's there. Sleeping Giants and its sequels are told almost entirely through interview transcripts conducted by an unnamed, evasive interrogator, giving the series a documentary, oral-history feel unusual for first-contact SF. The mystery escalates from an archaeological puzzle into a question of who else is looking for the same answer.