An accident at sea cripples a Royal Navy expedition 200 miles from finding the Northwest Passage, forcing its captains to make a dire choice.

After a long winter trapped in the ice, scouting parties are sent out in search of open water. One of the teams makes a frightening discovery.

With something now stalking the ships, the captains debate their options, testing their loyalty to one another against their duty to their crews.

A cunning attack on the ships proves the men are not battling an ordinary bear and that the region's Inuit culture may hold a key to their survival.

A strange illness begins to show itself while another more familiar one jeopardizes the expedition's most valuable resource - its captain's judgment.

With the end of their provisions in sight, officers contemplate an 800-mile walkout while planning a party to raise the men's worsening spirits.

As the men begin their long march south for rescue, a series of shocking events underscores how vulnerable and exposed their situation has become.

The death of an officer under mysterious circumstances creates paranoia among the men. Crozier discovers some of the crew may be considering mutiny.

Hope comes in strange forms, and the question of what the men are willing to do to survive begins to be settled in both noble and horrifying ways.

The expedition's epic journey reaches its climax as men find themselves in a final confrontation with the Inuit mythology they've trespassed into.