Dizi Adı: Grey's Anatomy
Bölüm Adı: I Will Follow You Into the Dark
Sezon/Bölüm: 5. Sezon 17. Bölüm
Yayın Tarihi: 12 Mar. 2009

Derek decides to quit after learning that more of his patients have died than survived; Izzie’s interns make an unsettling discovery about “Patient X.”