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 shorthanded ER to spring into action.
Callie makes a decision about her relationship; the doctors receive devastating news.
Meredith and Derek adjust to life at home with a newborn but find it difficulty being away from the hospital; Arizona tries to takes steps to fix her broken marriage; Alex and Jo navigate through their new relationship; and Owen clashes with Jackson over financial issues at the hospital. Meanwhile, April anxiously awaits her boards results
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 on a very special 200th episode.
Meredith jumps back into work but finds it hard to excel at both motherhood and being a surgeon. Stephanie tries to make a good impression on Jackson's mom, and Jo finds herself overly involved with her new patient. Meanwhile, Callie and Owen deal with an emotional situation regarding 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.
It's Halloween and the doctors of Grey Sloan Memorial are hit with a barrage of spooky patients, which affects their own plans and puts one doctor's well-being in jeopardy. Meanwhile, Derek collaborates with Ben on a new surgical technique, and Richard angers Bailey when he asks a second year resident to perform his next surgery.
The issues between Meredith and Cristina hit a boiling point when one of them ultimately betrays the other at the hospital. Derek tells Jackson that he needs to let go and allow the second year doctors to work on his patients, and April and Matthew make a bold decision about their relationship. Meanwhile, Bailey has difficulties with Ben’s return.
When an unexpected malpractice suit turns Callie's world upside down, her supportive father (Hector Elizondo) 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.
On the day of April’s wedding, the Grey Sloan Memorial doctors are all preoccupied with their own drama. Meredith and Cristina continue to argue about their research and careers, Bailey comes clean to Ben about her feelings regarding him moving back to Seattle, and Shane puts himself in a risky situation. Meanwhile, Derek gets a phone call that will change his life.
The doctors face the consequences of the events that took place at April’s wedding. Meredith feels betrayed when Derek goes back on a promise, Alex is furious after returning to the hospital and hearing the news about his father, and Arizona and Callie decide whether or not to move forward together. Meanwhile, Bailey realizes she was wrong about the motive behind Ben’s decision to move back to Seattle
After an anonymous complaint is issued by one of their own, the hospital implements a non-fraternizing policy causing the couples to panic. Meanwhile, Emma and Owen talk about the future, Cristina and Meredith enjoy a little girl time and Richard enlists the residents to help research a rare cancer case.
Arizona has a bad day which escalates when she advises one of Callie’s patients on a potential double amputation. Derek goes back on a promise to Callie, and Jo and Stephanie come across an abandoned baby outside the hospital.
Bailey asks Richard to join her on the case of a lifetime; Callie shocks Derek.
Cristina thinks about her future; a patient decides whether to live or not.
The doctors are exposed to flu-infected patients; Derek prepares to give a speech.
Cristina won't let herself get excited when she is nominated for a Harper Avery award.
Meredith helps Cristina draft a speech; Derek feels stressed; April and Jackson are at odds.
Jackson must deliver bad news to the doctors; Derek's sister visits; Richard surprises Catherine.
Cristina considers her future at the hospital; a surgery involving conjoined twins.
Meredith learns Amelia's true feelings about Seattle; Bailey deals with consequences.
The doctors bid Cristina farewell; a possible act of terrorism rocks the city.