... Explorers have found rock cairns with messages from sailors who abandoned ship. They've taken oral history from Inuit people whose ancestors saw the ships get stuck in giant ice floes. In several cases, they've dug up the bones and preserved bodies of the ship's crew. But they've found no ships, no logs, and no sign of Franklin himself.

In subsequent years, a rough sketch of the troubles emerged. During the first winter, the crew disembarked, travelled south to hunt. Franklin left a reassuring message in a rock cairn, signed "All well". A month later, he was dead.

A year later, the crew returned to the cairn and updated the note. By that time, 15 sailors had died.

"If it had just been that, it would have been one of the biggest disasters of Arctic exploration," says Ted Betts, a Toronto lawyer and author of the blog Franklin's Ghost. But it wasn't just that.

From that time on, things only got worse. The men, sickened from scurvy, tuberculosis and lead poisoning, got weaker and weaker. They reportedly abandoned ship in 1848, only to meet a cold death elsewhere...