: The doctors struggle to save a "John Doe" severely disfigured after jumping in front of a bus to save a stranger. Simultaneously, Izzie Stevens undergoes a risky brain surgery that leaves her with temporary memory loss.
: The episode’s climax occurs when the "John Doe" traces "007"—George O'Malley's nickname—into Meredith’s hand, revealing his true identity just as both he and Izzie begin to flatline.
Depending on your interest, here is a review of that episode and other notable works with the same title: 1. Grey’s Anatomy : Season 5, Episode 24 ("Now or Never")