Cristina, back from her honeymoon trip, searches in vain for Burke; Meredith, Cristina, Izzie and Alex spend their first day as residents with their own groups of interns.
The residents and interns treat the victims of a massive explosion at an apartment building; Mama Burke returns to collect her son's things; Lexie tries to have a heart-to-heart with unwilling Meredith.
George's skill level dazzles the new interns; Meredith half-heartedly helps Lexie with her first emergency patient.
Cristina and Burke's wedding day arrives; the interns get their exam results; Callie and George make a decision about their relationship.
Bailey and Seattle Grace's new paediatric surgeon try to save the life of a longtime patient; the admission of a death row inmate angers Derek; Izzie tells Alex that she has been seeing Denny.