The men on board he HMS Terror-part of the 1845 Franklin Expedition, the first steam powered vessels ever to search for the legendary Northwest Passage-are entering a second summer in the Arctic Circl without a thaw, straded in a nightmarish landscape of encroaching ice and darkness. Endlessly cold, they struggle to survive with poisonous rations, a dwindling coal supply, and ships buckling in the grip of crushing ice. But their real enemy is even more terrifying. There is something out there in the frigid darkness: an unseen predator stalking their ship, a montrous terror clawing to get in.