Perhaps it was no surprise that part of the crew had become deranged. Surviving an Arctic winter aboard an icebound ship was a frightful challenge. Bound for months in darkness and unrelenting cold, the men were trapped in the cramped confines of the ship’s lower deck. There they battled rats, claustrophobia, and isolation, in addition to the physical ravages of scurvy and frostbite. Passing a single winter was difficult enough, but Fitzjames’s crew was coming off a third consecutive Arctic winter, their ills compounded by short rations of food and fuel. The death of their expedition leader, Sir John Franklin, earlier only added to the fading sense of optimism.

Yet Fitzjames knew there was something more sinister at work. When a bosun’s mate tore off his clothes, climbed topside, and ran screaming across the ice floes, it could have been marked down as a single case of dementia. But when three-fourths of the crew began yelling in their sleep, staggering around listlessly, mumbling in confused speech patterns, and hallucinating, there was clearly something else at play. When the behaviors gradually turned violent, Fitzjames had the afflicted quietly moved to the forward deck and sequestered.

“It’s something on the ship driving them mad,” Fairholme said quietly, as if reading Fitzjames’s mind.

Fitzjames started to nod in reply when a small crate came hurtling off the upper reaches of the barrier, nearly striking him in the head. The pale face of an emaciated man burst through the opening, his eyes glowing red under the flickering candlelight. He quickly squeezed himself through the opening and then tumbled down the face of the barrier. As the man staggered to his feet, Fitzjames recognized him as one of the stokers for the ship’s coal-fi red steam engine. The stoker was shirtless despite the freezing temperatures inside the ship, and in his hand he wielded a heavy butcher knife taken from the ship’s galley.

“Where be the lambs for slaughter?” he cried, holding up the knife.

Before he could start slashing, one of the Royal Marines countered with a musket stock, striking the stoker on the side of the face. The knife clanged against a crate as the man crumpled to the deck, a trickle of blood running down his face.

Fitzjames turned from the unconscious stoker to the crewmen around him. Tired, haggard, and gaunt from an inadequate diet, they all looked to him for direction.

“We abandon ship at once. There is still more than an hour of daylight left. We will make for the Terror. Lieutenant, bring the cold-weather gear up to the Great Cabin.”

“How many sledges shall I prepare?”

“None. Pack what provisions each man can carry but no extra equipment.”