The doctors of Grey Sloan Memorial Hospital Meredith Grey are faced with life-or-death decisions on a daily basis. They seek comfort from one another, and, at times, more than just friendship. Together they discover that neither medicine nor relationships can be defined in black and white.
Meredith and Derek learn that "happily ever after" isn't easy, and a military doctor who brings in a trauma patient catches Cristina's eye.
Cristina's treated by Major Hunt after being impaled by an icicle and Meredith and Derek finally reach a conclusion about moving in together.
A plumbing leak becomes a deluge and wreaks havoc at Seattle Grace, as the Chief attempts to implement new teaching policies.
Meredith freaks out when Derek discovers her mother's old diary in the house and Cristina stumbles into a part of the hospital that she's never seen before.
Bailey heads up a team of surgeons performing a "domino procedure" in which each surgery hinges on the one preceding it.
To help Bailey become a better surgeon, the Chief gives her new power, new responsibility, and the challenge of removing a girl's inoperable tumor.
The Chief announces to the residents that a solo surgery will be awarded, and the news sends them into a competitive frenzy.
One of Meredith's oldest friends, Sadie, becomes an intern at Seattle Grace, but Mer's friends are less-than-welcoming to her.
Meredith, Cristina and Bailey come to Lexie and Sadie's rescue when a surgery goes horribly wrong.
Cristina is awarded the first solo surgery among the residents, but must give it up and choose her replacement.
Bailey teams with Seattle Grace's new pediatric surgeon, Dr. Arizona Robbins, to save the life of a young patient.
Derek's mother makes a surprise visit to Seattle and meets Meredith for the first time, as Mark tries to conceal his relationship with Lexie from her.
Bailey grows desperate as a patient's condition becomes more and more dire.
Now that Derek has the engagement ring, he searches for the perfect way to propose to Meredith, as Lexie demands that she and Mark go public.
Addison, Naomi and Sam rush the ailing Archer to Seattle Grace and reunite with old friends Derek and Mark to help save his life.
Derek's confidence is shaken like never before as he faces off with Addison over what course is best for their dying pregnant patient.
After learning at a deposition that more of his patients have died than survived, Derek decides to quit, even as Meredith refuses to give up on him.
Derek refuses to return to SGH and it takes a visit from the Chief himself to set him straight; Izzie's cancer secret comes out.
Some of Izzie's friends fail to rally around her as Derek must overcome his fears in time to remove her deadly brain tumor.
As she endures aggressive treatment for her cancer, Izzie throws herself into planning Derek and Meredith's wedding.
Izzie gets a surprise visit from her mother (Sharon Lawrence); Thatcher tries to make amends with Meredith and Lexie; Meredith and the Chief argue over a controversial case.
Derek and Meredith get ready for their wedding; college students injured in a car accident are admitted to the ER; Izzie starts experiencing familiar symptoms.
Izzie spends time with a fellow cancer patient and contemplates whether or not to undergo a risky surgery and George makes a big decision of his own.
George delivers stunning news to Bailey, sending shockwaves throughout the hospital, and Izzie's friends anxiously await her recovery from surgery.