When famous surgeon Dr. Harper Avery is rushed to Seattle Grace-Mercy West, the staff is surprised to discover that one of their own is related to this legend, and his unorthodox request for his surgery causes tensions t between Derek and Richard. Meanwhile Callie and Arizona try to help Teddy and Sloan move on from their pasts and find greener pastures.
Callie, Bailey and Richard present pivotal surgical cases from their pasts when Derek restores the hospital lecture series.
A roof collapses on a restaurant known as a trysting spot on Valentine's Day, interrupting whatever romance plans the doctors might have had. Nonetheless, Arizona and Callie play Cupid---for Bailey and an anesthesiologist named Ben (Jason George). Callie also teams up with Mark to help persuade Sloan (Leven Rambin) to do the right thing for her baby. Meanwhile, Derek struggles to manage his time in his new role as chief, and Meredith wrestles with what being the chief's wife entails.
After being named interim chief, Derek begins to settle into his new position but faces a lawsuit when Bailey and Meredith's patient wakes up during surgery. Meanwhile, Teddy refuses to let Cristina be a part of her service, Alex continues to work with Arizona in pediatrics, and Mark avoids talking to Lexie who is still heartbroken over their break up.
Derek confronts Richard over his alcoholism in an attempt to help his friend and the hospital. Izzie returns to reconcile with Alex, and tensions between Teddy, Cristina and Owen escalate.
Mark flies Addison to Seattle so that she can help perform a difficult procedure on his pregnant daughter. Meanwhile, Owen begins to question Teddy's motives when she has Cristina be the lead on a complex surgery; and Derek becomes suspicious when the Chief has Meredith assist on a high-profile operation.
As the holidays come and go, Miranda has a surprise visit from her father, William, who has a strong disapproval of her choices in life. Mark and Lexie must cope with a person who re-enters Mark's life, and Thatcher Grey questions the Chief's behavior, but Meredith is quick to come to the Chief's defense.
Owen recruits Dr. Teddy Altman a former Iraqi veteran, as the new cardiothoracic surgeon, Cristina questions her abilities in the E.R. and relationship with Owen. Izzie returns to Seattle Grace with her high school mentor seeking treatment for his dementia. Richard's responsibilities, post-merger, are taking a toll on him.
A generous 25 million donation is offered to Seattle Grace by the parents of Arizonas 10-year-old patient, she finds herself in a conflict of interest when his condition worsens. Cristina tests her boundaries with Owen at the hospital. Alex is left with all of Izzies hospital bills to contend with.
When the hospital lab tech, Isaac, discovers he has an inoperable tumor wrapped around his spine, he turns to Derek for help; Derek challenges Richard's authority.