Geologist and adventurer Philip Mercer is visiting an old friend who's working far down in Minnesota's Leister Deep Mine--but he arrives too late to save Abe Jacobs and his climate-research team from a shocking, brutal attack. Mercer vows to seek revenge as well as answers, hoping to pick up Jacobs's search for a cache of the rare crystals known as lightning stones--rumored to have been aboard Amelia Earhart's plane when it vanished in 1937. From...