A blizzard moves into Chicago, stranding a family in the snow. Abby and Pratt quickly try to save the family. A gang shooting challenges Morris and Pratt. Meanwhile, Luka and Abby begin making wedding plans, but their engagement might not be very secret; Gates struggles with the reappearance of his father and the possibility of losing Sarah; and Neela becomes jealous when Dubenko brings in a new surgical intern.