At America's base at the South Pole, 26 "winterovers" complete the yearly ritual of waving good-bye to the "last plane out," then summon their energies for that season's battle with constant darkness, total isolation, and murderous cold that can dip well beneath 100 degrees below zero. Little does the group guess that in succeeding days and weeks, they'll be tested not just by unimaginable weather extremes, but by a murderer intent on gradually eradicating them.