As Meredith nervously awaits a final decision from Derek, her fear is interrupted when a train crash brings several seriously injured patients to the hospital. The doctors must make a tough decision in order to save at least one of them. Meredith understands that Derek has chosen Addison, and is crushed. Alex fails to notice a woman bleeding internally and she eventually dies from her injuries. As Addison and Izzie work with two pregnant women, Addison sees great potential in Izzie, who must decide whether her loyalty as Meredith’s friend outweighs professional gain.