When two young men get lost in Alaska's mountainous wilderness, they slowly begin to die of exposure. As their senses become numb, they become aware of a third man traveling with them at times, and are too disoriented to make contact. When the two young men collapse in exhaustion and give themselves over to death, the mysterious third man appears again. Is he there to help, hinder...or is he even there at all?

Based on a phenomenon experienced in the real world by various adventurers including mountaineers on Everest and by the Shackleton survivors in the Antarctic, The Third Man redefines the modern ghost story.