Candice Afia

Meredith, Cristina, Izzie and Alex spend their first day as residents with their own interns, including George, repeating his internship after failing his exams, and Meredith's half-sister. Cristina searches for Burke, who is nowhere to be found and Richard resumes his position as chief of surgery.

The residents and interns treat the victims of a massive explosion at an apartment building, while Alex investigates the cause of the accident.

Tension arises between Derek and Meredith's mother; Cristina is mesmerized by the lifestyle of working in the dermatology wing.

Bailey arranges a domino kidney surgery involving all the residents and interns; Meredith is upset Derek didn't include her in the article on their clinical trial.

Bailey's patient, Jackson, continues to get worse; Callie catches Owen in Cristina's bedroom; after a big blowout fight, Izzie is forced to face the truth about what is going on.

Cristina and Burke's wedding day arrives - along with the interns' first exam results - and a successor to the Chief is named, as Callie and George make a big decision about their relationship.