"I Will Follow You Into The Dark" is the seventeenth episode of the fifth season of Grey's Anatomy and the 95th produced episode of the series. It is also the 121st produced episode of the Grey's Anatomy franchise. It was broadcast on March 12, 2009.
After making a mistake in the O.R which cost a patient their life, Derek spirals into a depression and, after learning his death rate statistic, decides to quit surgery in spite of Meredith's insitance that she won't give up on him. Izzie presents the interns with 'Patient X' in a bid to teach them while trying to come to terms with her own mortality and Bailey and Richard continue fight over her peads fellowship. Alex must go head to head with Owen and Arizona in order to save a life.
- "Every surgeron I know has a shadow. A dark cloud of fear and doubt that follows even the best of us into the O.R. We pretend the shadow isn't there hoping that if we save more lives, master harder techniques, run faster and father, it'll get tired and give up the chase. But like they say, you can't outrun you're shadow."
- "Every surgeron has a shadow and the only way to get rid of a shadow is to turn off the lights, to stop running from the darkness and face what you fear, head on."
- "Front Row" - Metric
- "Duet" - Rachel Yamagata
- "Treeology" - Shady Bard
- "A Storm Is Going To Come" - Piers Faccini
This episodes' title references the song I Will Follow You Into The Dark, originally sung by Death Cab For Cutie