The Grey Sloan Memorial Hospital doctors are faced with the devastation left by the storm. A giant mudslide in Seattle injures a group of first responders and citizens, causing the already short handed ER to spring into action. Meanwhile, Meredith is faced with a tough decision that will affect the life of a loved one, Callie is rocked by the reality of Arizona’s infidelity, and Richard’s life is in extreme danger.

Callie makes a decision about her relationship; the doctors receive devastating news.

Derek e Meredith se adaptam à vida em casa com seu recém-nascido; Arizona tenta reparar seu casamento; Alex e Jo navegam em seu novo relacionamento, Owen discute com Jackson sobre as questões financeiras do hospital. Enquanto isso, April espera ansiosamente os resultados da suas provas.

The doctors of Grey Sloan Memorial throw a fundraising gala which turns wildly competitive after Jackson makes a rash promise. Back at the hospital, Bailey’s patience is tested when she has to deal with several extremely difficult patients. Meanwhile, Shane and Stephanie handle an incredibly busy ER by themselves and Alex reveals an emotional secret to Jo.

Meredith struggles to balance her roles as a surgeon and a mother when she returns to work; Stephanie tries to impress Jackson's mother; Jo becomes overly involved with a patient.

Derek and Callie work on a brain mapping project, Richard encourages the interns to use his physical condition as a learning tool and after a discussion with Callie, Meredith considers continuing her mother’s research. Meanwhile, Shane continues to feel guilty about Heather’s death.

Costumed patients create a challenge for the doctors; Derek and Ben work on a new surgical technique; Richard asks a resident to perform his next surgery, angering Bailey.

A betrayal intensifies the issues between Cristina and Meredith; Matthew and April make a decision about their relationship; Bailey faces difficulties with Ben's return.

When an unexpected malpractice suit turns Callie's world upside down, her supportive father arrives and shares an interesting secret with her. Meanwhile, through flashbacks, we learn some surprising details about Callie and Arizona's marriage.

Ben worries that a casual conversation with Derek could potentially cause issues for Bailey, Cristina turns to Shane as tension grows with Meredith, and April's upcoming wedding makes for an uncomfortable situation between Jackson and Stephanie. Meanwhile, Meredith plans a Thanksgiving dinner at her house.

April’s sisters arrive to help celebrate April’s upcoming nuptials and quickly get on her nerves. Matthew and Jackson are forced to work together when they witness a terrible accident, Callie and Arizona work hard to reestablish their relationship and Cristina is pressured to live stream an upcoming surgery. Meanwhile, a familiar face returns to the hospital.

Os médicos são confrontados com as consequências dos acontecimentos no casamento de April; Meredith se sente traída quando Derek quebra uma promessa, e Alex fica furioso com o que aconteceu ao seu pai. Callie e Arizona resolvem dar um passo importante em seu relacionamento e Bailey não entende Ben quanto a sua decisão de voltar para Seattle.

Depois que uma reclamação anônima é feita por algum dos médicos do hospital, o Grey Sloan Memorial implementa uma política de “não confraternização”, causando pânico nos casais. Enquanto isso, Emma e Owen falam sobre o futuro, Cristina e Meredith aproveitam um tempo de garotas e Richard lista os residentes para ajudar em uma pesquisa sobre um caso raro de câncer.

Arizona está em um dia ruim que se agrava quando ela aconselha um dos pacientes de Callie com potencial de amputação dupla. Derek quebra uma promessa feita à Callie; Jo e Stephanie encontram um bebe abandonado do lado de fora do hospital. Enquanto isso, os médicos estão repercutindo a regra de que inclui a suspensão de um médico.

It's Richard's birthday and Bailey invites him to scrub in on the case of a lifetime. Meredith hires a research assistant to help with her portal vein project. A scorned Callie gives Derek quite the shock. Meanwhile, Shane helps screen candidates for Cristina's clinical trial and meets a young expectant mother who needs his help.

Cristina imagines the two routes her life can take based on one decision she makes. Meanwhile one of the hospital’s patients decides whether or not to live.

The hospital gets inundated with flu infected patients, which causes the doctors to slowly fall ill one by one. Derek must fight off the sickness as he prepares to give a speech on brain mapping and the residents place bets on who will fall ill first. Meanwhile, a new doctor at the hospital gives Alex a glimpse into an alternate form of medical practice.

Cristina won't let herself get excited when she is nominated for a Harper Avery award; Alex thinks about making a change; Callie and Derek work with a machine that recognizes emotions.

Cristina enlists Meredith to help her prepare an acceptance speech for her possible Harper Avery win and while Owen offers to attend the ceremony with her, she insists on going alone. Meanwhile, Derek feels overwhelmed between his responsibilities at home and at the hospital. April and Jackson come to a disagreement on children and religion, and Callie and Arizona try to reconnect in their marriage.

Jackson is given the daunting task of delivering disappointing news to the doctors. Meanwhile, Derek's sister Amelia drops by for a surprise visit, Richard surprises Catherine in Boston and when Bailey gets frustrated by the slow pace of her research, she makes a risky decision.

Cristina considers her future at the hospital; Amelia and Derek collaborate on a tough surgery involving conjoined twins; Jo takes on too many cases at once; Stephanie stumbles on the truth about Bailey's case.

With Derek away, Meredith spends time with Amelia and finds out her true feelings about her time in Seattle. Bailey deals with the ramifications of her actions and Callie receives devastating news. Meanwhile, the residents panic after hearing that one of them will be fired

The doctors of Grey Sloan Memorial Hospital bid an emotional farewell to the beloved Cristina Yang. A possible act of terrorism rocks Seattle and causes chaos at the hospital. Meanwhile, Meredith makes a life changing decision and one doctor receives shocking news.