Within that framework, the specific physiological events of those six hours cannot be reconstructed with precision.

The body’s own mechanisms — the vasoconstriction, the metabolic depression, the cardiovascular triage that protected her core at the expense of her periphery — operated in the dark and the cold without any monitoring, without any record.

What emerged from that dark was a young woman who was talking by noon.

What Remains Unexplained

Science has come a long way in understanding hypothermia since 1980.

The development of active internal rewarming techniques — extracorporeal membrane oxygenation (ECMO) and cardiopulmonary bypass — has made possible the rescue of patients with far more profound hypothermia than Jean Hilliard suffered, including patients in cardiac arrest with core temperatures as low as 56 to 57 degrees Fahrenheit, who have been resuscitated with minimal lasting neurological damage.