Two ships, brave captains and their crews, royal marines, all battle the elements and unknown adventure while remembering home and mission beginnings.
A title card informs the viewer that Sir John Franklin's Arctic expedition of 1845 to find the Northwest Passage was never seen again. In the opening sequence set in 1850, Sir James Ross and his translator are speaking to a Netsilik man in a tent who encountered the expedition's last survivors under the leadership of Captain Francis Crozier. The man informs Ross and his interpreter they were heading south overland and pursued by a creature called the "Tuunbaq". The man informs the two Crozier is dead but before he died, asked the man to tell those who may come looking for him that the ships are gone, there is no Northwest Passage, and that he along with his men, are now "dead and gone."
Four years earlier, in September 1846, the Royal Navy expedition and the ships HMS Erebus and HMS Terror are in the Arctic Archipelago close to King William Land. The expedition runs into difficulty when a collision with an iceberg damage Erebus's propeller and two men are also lost. Francis Crozier, captain of Terror and second-in-command of the expedition, becomes concerned about getting stranded in the pack ice above the Arctic Circle through winter. He recommends to Sir John that they shift all men from Erebus to Terror and steam east around King William Land which Crozier believes to be an island to avoid becoming trapped in the winter ice. Franklin overrules Crozier's concerns and presses the expedition further west in the belief that the ships can complete transit before the onset of thick ice. Before the ships can reach open water however, they become frozen and trapped.
- A slightly different version of the episode exists in which the pre-credits sequence is altered from the one which originally aired. In it, Crozier expresses his dislike dining with Sir John and Commander James Fitzjames with Thomas Blanky on the deck of Terror, the scene where Cornelius Hickey, Thomas Evans, William Strong, David Young, and Robert Golding are discussing Neptune's rank is one long scene, the discussion Crozier and Thomas Jopson have about nearing and finding the Northwest Passage is shorter, the dining scene with the officers is extended, Fitzjames's remarks about Ross is omitted, and Strong talks about how magnetic energy in the Arctic allows hair to grow faster.
- When Crozier points out that only 4 men at the table at Erebus' officers meeting had been to the Arctic before, this is incorrect. Graham Gore who attended the meeting, had been to the Arctic on Sir George Back's 1836 expedition aboard HMS Terror.