Sam treats an abused and newly pregnant teen, Layla (RHEAGAN WALLACE), as well as a woman, Kathy (MARIN HINKLE - "Two and a Half Men"), who could lose her entire family after a car accident. Carter takes the day off to show Kem (recurring guest star THANDIE NEWTON) the wonders of a wintry Chicago. Meanwhile, a risk-assessment expert, Arnie Nadler (RICHARD KLINE), is hired to observe the emergency room and is shocked at the abounding mayhem--especially when Sam gets violent with Layla's obnoxious boyfriend. Abby and Pratt restrain an undocumented man, Miguel (F.J. RIO), who wants to leave despite testing positive for tuberculosis. And Sam is quizzed by her son, Alex (recurring guest star OLIVER DAVIS), about her interest in Kovac.