The men on board HMS Terror have every expectation of triumph. As part of the 1845 Franklin Expedition, the first steam-powered vessels ever to search for the legendary Northwest Passage, they are as scientifically supported an enterprise as has ever set forth. As they enter a second summer in the Arctic Circle without a thaw, though, they are stranded in a nightmarish landscape of encroaching ice and darkness. Endlessly cold, with diminishing rations, 126 men fight to survive with poisonous food, a dwindling supply of coal, and ships buckling in the grip of crushing ice. But their real enemy is far more terrifying. There is something out there in the frigid darkness: an unseen predator stalking their ship, a monstrous terror constantly clawing to get in.