Vincent has carefully prepared for his trip through the frozen tundra. Though the day is extremely cold — even considering the locale — he feels strong enough to challenge nature. When he stops to a quick bite to eat, however, his fingers frosted much more quickly than he expected. He employs his usual tactics: running briskly for a few minutes, rubbing his hands against his cheeks, and all seems fine. His plans, however, are quickly ruined when he falls through ice into a few feet of freezing water. As his body succumbs to numbness, he attempts the simple task of building a fire — a simple task that could save his life:
...Great care must be exercised; that with failure at the first attempt, the chance was made greater for failure at the second attempt. In short, he knew that there must be no failure. The moment before a strong, exulting man, boastful of his mastery of the elements, he was now fighting for his life against those same elements — such was the difference caused by the injection of a quart of water into a northland traveller's calculations.
The reader is led to worry: will he survive?
No need for concern; the story is aimed for children and, naturally, has a happy ending and a lesson learned. London apparently was not satisfied by this and, some years later, re-wrote "To Build a Fire." This version is much darker and the narrator, now unnamed, has with him a canine companion. In the last few paragraphs, the story is told through the eyes of that dog in a method reminiscent of his novel The Call of the Wild (also set in the Klondike), which he published shortly after his first version of "To Build a Fire." In the later version of the story, there is no life lesson for the narrator to learn.