Agroupofdiverseindividualsaresuddenlytakenfromtheirhomesandflownviahelicoptertoafuturisticbombshelterinthedesert,one-thirdofamilebelowthesurfaceoftheEarth.There,theylearnthatanuclearholocaustistakingplaceandthatthey'vebeen"chosen"bycomputertosurviveintheshelterinordertocontinuethehumanrace.Theshelterisdesignedtoallowthepeopletoexistundergroundcomfortablyforyears,buttheyarefacedwithathreatnobodycouldhavepredicted:acolonyofthousandsofbloodthirstyvampirebatsfindsawayintotheshelterandlaunchesaseriesofviciousattackswheretheyclaimthehumansonebyone.