A gripping adventure from the NEW YORK TIMES bestselling author of MAP OF BONES and THE DOOMSDAY KEY. Beneath the ice at the bottom of the Earth is a magnificent subterranean labyrinth, a place of breathtaking wonders - and terrors beyond imagining.A team of specialists led by archaeologist Ashley Carter has been hand-picked to explore this secret place and to uncover the riches it holds. But they are not the first to venture here - and those they follow did not return.There are mysteries here older than time, and revelations that could change the world.But there are also things that should not be disturbed - and a devastating truth that could doom Ashley and the expedition: they are not alone.