In the Season 1 finale, a mysterious illness sends the hospital into lockdown; and leaves Alex fighting to save the lives of Jesse, Pierce and Ji-Sung. In other events, Millicent deals with the consequences when Alex disobeys the CDC; and an elderly man's search for his missing wife causes Alex to make a major decision about her love life.

Cast: Melissa George, Don Hany, Dave Annable, Shelley Conn, Joshua Leonard, Jamie Kennedy, Maya Erskine, Rudy Martinez, Caitlyn Larimore, T.J. Alvarado, John Balma, Bryan Espino, Erica Ikeda, Denell Johnson, Lenora May