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

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 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 a tough, risky strategy while struggling to raise the men's worsening spirits.

As the men make new attempts to find rescue, a series of shocking events underscores how vulnerable and exposed their situation has become.

Deaths under mysterious circumstances create paranoia among the men, and 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.