Izzie and George's new-founded relationship results in them having bad sex. Callie's Chief Resident position is taken away from her, and Bailey is the humble replacement. Meredith can barely handle it with Lexie anymore.

Derek's confidence is shaken like never before as he faces off with Addison over what course is best for their dying pregnant patient; Cristina calls the abilities of a renown surgeon into question after she botches a standard procedure; and Bailey, who has decided to pursue a fellowship in Pediatrics, is appalled by the Chief's less-than-stellar recommendation letter.

The hospital staff is left to deal with the aftermath of George's passing. Hitting the staff hard, they all find unique ways to get through the various stages of grief. George's mom returns, faced with the difficult task of deciding what to do with his organs.

Several weeks after her near-death experience, a recovering Izzie returns to work. Meanwhile, nervous that there will be layoffs in the hospital in the wake of an announcement from the Chief, the Seattle Grace residents compete to survive the cuts, including Cristina, who attempts to work alongside Arizona in pediatrics. And Bailey and Alex's patient's already complex case is further complicated by her schizophrenic son.

The residents of Seattle Grace and Mercy West vie for surgeries and their careers as day one of the hospital merger begins. Meanwhile, Arizona stands by an enraged Callie when her father, Mr. Torres, employs a priest to help convince her to date men, and Izzie experiences the brunt of her new surgical competition.

When Isaac has an inoperable tumor wrapped around his spine, he wants Derek to do the impossible. Derek tests the Chief's authority when Richard objects to moving forward with the risky surgery.

Mark flies Addison to Seattle to help with a difficult procedure on his pregnant daughter, Sloan, Owen questions Teddy's motives when she assigns Cristina the lead on a complicated surgery, and Derek's suspicions are raised when the Chief recruits Meredith to assist with a high profile operation on.

An elderly patient admitted into the E.R. for a heart condition sees a familiar face, a long lost love who happens to be in the E.R. as well for a fractured arm, and the staff find themselves caught up in their love story. Meanwhile, Karev treats a troubled teenage patient (guest star Demi Lovato) whose parents brought her in for schizophrenia, and Meredith can't help but tell Cristina about her suspicions of Owen -- which inevitably messes with Cristina's head.

Owen puts the residents through a rigorous trauma certification drill; Cristina is left alone to monitor an ill lung transplant patient.