Yesterday they were students, today they're doctors at Seattle Grace Hospital, and, in a world where on the job training can be a matter of life and death, they're all juggling the ups and downs of their own personal lives.

The staff try to be optimistic as a young woman clings to life after a brutal attack. Meanwhile, Meredith puts her career on the line to save a newborn in the hospital nursery, and the others learn that it takes more than just medical knowledge to be good at their jobs.

When the annual bicycle messenger race takes place in Seattle, the hospital emergency room fills with an assortment of injuries, causing the interns to compete for the most severe cases. Meanwhile, Derek and Burke compete for the chief resident position.

Cristina's encounter with a former nurse, now a patient, changes her forever. Derek and Meredith treat a construction worker who has miraculously survived an injury but is now faced with tough decisions about his future, whereas Izzie becomes the topic of hotel gossip.

An exhausted Meredith thinks she may have made a mistake during surgery, which could jeopardise her career. Meanwhile, Izzie's plan to throw a party for her new boyfriend goes completely awry, and Alex deals with a patient who is addicted to painkillers.

Alex gains the trust of Annie, a patient with a very large tumour, only to humiliate himself in front of her later. Derek chooses Meredith to assist with an elderly Parkinson's patient but Bailey disapproves of their relationship and is set on making Meredith suffer.

Derek and Meredith spend the night together and their haggard appearance speaks volumes to everyone. George suspects an anaesthesiologist of drinking on the job but is reluctant to speak up about it, and Alex treats an old schoolmate who finds honour in self-mutilation.

Alex treats a patient whose religious beliefs jeopardise her chances for recovery. A pregnant woman, diagnosed with cancer, disagrees with Cristina's medical advice, and the interns are mystified by a patient who's being treated for seizures and who thinks he's psychic.

An STD outbreak affects several members of staff prompting Webber to call a meeting. Izzie and Cristina are worried by a patient's family who are at odds over his care, and Burke treats a college buddy whose diagnosis raises some questions regarding his wife's actions.