A blizzard has left Chicago blanketed in two feet of snow -- and the ER is completely bereft of patient activity. But no sooner does the staff try to take advantage of their unexpected "layoff" than disaster strikes in the form of a horrendous 32-car pileup. In the midst of the ensuing chaos, Dr. Angela Hicks (CCH Pounder) makes her first appearance. Meanwhile, Carol (Julianna Margulies) has a surprise in store for her colleagues. ~ Hal Erickson, Rovi