Scott Michael Morgan

The surgical staff tries to be optimistic as a young woman clings to life after a brutal attack. Meanwhile Meredith puts her career on the line to save a newborn in the hospital nursery, and the other interns learn that it takes more than just medical knowledge to be good at their jobs.

Susan eases her overwhelming feelings of guilt by making some dangerous choices, and Gaby plans a sexy surprise to help Carlos gain his sexual mojo back.

Well-connected Special Agent Emily Prentiss joins the team, as they take on two serial killers, who seem to be in competition with each other.

It's Christmas time and both Marshall and Robin are feeling homesick in New York, and Ted's immature younger sister Heather arrives in the city. Ted has been trying to keep Heather and Barney apart because he fears they will sleep together. Barney and Heather prove Ted wrong and Ted is forced to admit that his sister has grown up.

In the midst of flu season, a sick Leslie and Andy struggle to book performers for the Unity Concert.

Jim and Cheryl argue about the actor Erik Estrada, and Jim disputes something that happened ten years ago.