Summary: Seattle Grace Hospital is hit with a crisis like no other in its history.

In the second hour of the season finale, Cristina and Meredith’s surgical skills are put to the ultimate test.

The hospital is hit with an unprecedented crisis; Meredith and Cristina’s surgical skills are put to the test.

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 whose parents brought her in for schizophrenia, and Meredith can’t help but tell Cristina about her suspicions of Owen.

Bailey preps the team with mandatory sensitivity training prior to admitting a 700-pound patient with compounded medical issues, and the case proves to be challenging in every sense of the word. Meanwhile Derek has to come face to face with a former patient’s husband in a wrongful death deposition, and spending time with a heart patient’s daughter opens up some old wounds for Cristina.

Sloan returns to Mark’s apartment just as she’s going into labor. Teddy, Mark and the still-fighting Callie and Arizona are there to help with the birth and to get Mark through his grandson’s pending adoption. Meanwhile Teddy sees Derek’s invitation to illustrious cardiothoracic surgeon, Tom Evans, as a threat to her future employment at the hospital The team works on a crab boat captain who has been stabbed with a giant shark hook.

Alex asks Bailey to approve his younger brother Aaron’s hernia repair pro bono. When Aaron says that Alex hasn’t been home since he got to Seattle, some of Alex’s past secrets are revealed.

Teddy’s patient seeks to end treatment and her life, she turns to Owen for help. Callie and Arizona have a difference in opinion on what their future holds. Richard tries to adjust to his role as a surgeon.

A patient arrives at the hospital in need of a complex surgical procedure, and Richard is furious when Derek chooses Owen to do it over him. Meanwhile, Bailey nervously prepares for another date with Ben.

When Dr Harper Avery, the namesake of the Avery award, is rushed to the hospital, his unusual request for surgery heightens tension between Derek and Richard. The doctors are surprised to learn that Jackson is the medical legend’s grandson. Meanwhile, Callie and Arizona help Mark and Teddy move on from their rocky past relationships.