In the November 4 episode, Elisabeth Moss is a cancer patient who wants Veronica to let her die after going through a painful chemotherapy.
"Mercy" will present a moving performance by Elisabeth Moss next week in the episode called "The Last Thing I Said Was". The "Mad Men" star had done a guest appearance as a courageous cancer patient whom Veronica takes cue from to confess to her husband Mike that she's been in a secret affair with Dr. Sands.
Meanwhile, Sonia gets relationship advice from an experienced patient and begins to question her arm's-length approach to dating, just as her cop-boyfriend Valentino goes missing. Chloe plans a reunion with a former boyfriend but her evening takes an unexpected turn when she learns some surprising news.
Elisabeth Moss made her break on television starring as Zoey Bartlet on "West Wing". She is currently a regular actress for AMC's Emmy-winning series "Mad Men", playing copy writer Peggy Olson.
"Mercy", a new medical series from the perspective of the nurses, has been picked up by NBC for a full season. It was previously benched for a 2010 premiere before "Parenthood" suspended its production due to a cast change.