Maggie reevaluates her life choices after receiving an invitation to her ex-boyfriend's wedding; Richard questions Bailey's loyalty, and Jo confides in Stephanie about a secret she's been keeping from Alex. Meanwhile, Alex struggles with making a difficult decision that will affect the lives of newborn twins. The doctors of Sloan-Grey Memorial Hospital deal with life-or-death consequences on a daily basis - it's in one another that they find comfort, friendship and, at times, more than friendship. Meredith's (Ellen Pompeo), along with interns Cristina Yang, Izzie Stevens, George O'Malley and Alex Karev's, medical world revolved around textbooks and professors yesterday, but today they are experiencing medicine first-hand as surgical interns at Seattle Grace Hospital, a teaching hospital with one of the toughest residency programs in the nation. Here, they must learn to balance their personal lives with their highly competitive professional lives, all while dealing with the daily stress of life and death situations. Together they're discovering that neither medicine nor relationships can be defined in black and white. Real life only comes in shades of grey.