The tiny bone fragment of life that persisted in Jean Hilliard’s frozen body on December 21, 1980 — twelve beats per minute, a barely audible whimper — is what stands between her story being a survival story and her story being a tragedy.

The margin was that small.

That she survived, that the margin held, that the heating pads worked and the heart found its rhythm and the young woman was talking by noon: this is the fact at the center of an extraordinary story.

The mystery is not why she died.

She didn’t.

The mystery is how a body got that close to the edge of cold and came back.

That mystery remains, in the fullest and most honest sense, partially open.