Grey's Anatomy: Season Finales Ranked

Richard is determined to discover the guilty party, and punishes the interns by making them arrange a prom for his niece. Meanwhile, Callie presses George about his feelings, and Derek and Meredith have to make a decision about Doc.

Cristina and Meredith's surgical skills are put to the ultimate test.

George finally gets laid but gets syphilis. It's rampant among staff. Surgeon Webber is losing his sight. He wants Shepherd to operate secretly. A male patient has an ovary. A lifesaving autopsy's performed without consent.

The wedding day arrives. Richard chooses the new Chief and Chief Resident, the interns receive their exam results, Callie drops a bombshell on George while Izzie pours her heart out to him, and Burke makes an important decision.

Cristina must head to Zurich soon but she is unprepared to leave behind her life in Seattle. Fear runs amok throughout the hospital as an explosion in a shopping mall results in a mass casualty situation.

As Meredith, Cristina, Derek, Mark, Lexie, and Arizona face the aftermath of their accident, the doctors back at the hospital face the future that seems to be taking them all in different directions.

Meredith and Derek are at odds over whether or not to continue with their 13th clinical trial patient and the doctors lift the final critical pieces of cement from the young boy's body. Meanwhile, Alex rushes Ava into the hospital and is forced to confront the reality of her condition.

Izzie's memory problems panic Alex, the team takes care of a John Doe who was hit by a bus, Bailey rethinks her pediatrics fellowship, and the hospital endures losses.

As Seattle is plunged into a major storm, Meredith goes into labour. When the hospital loses power, her doctor and all the others are forced to work in the dark. Cristina must perform surgery in almost complete darkness while Arizona, Alex, and Lauren must ward off terrified parents. Then, just outside the hospital, a school bus full of people crashes and flips over, forcing several doctors to rescue its passengers. Cristina finally confronts Owen on his desire to have kids.

While Meredith faces the consequences of tampering with the trial Cristina and Owen fight over an unexpected pregnancy.

As the doctors continue to tackle an unfathomable crisis, they are reminded of what is important and brought closer together.