As Bailey puts her wedding on hold to tend to Adele, a biker gang floods the hospital with injuries for all the other doctors to tend to. Meanwhile, Cristina and Owen make a final decision about the divorce and Callie and Arizona try to reconnect.
The survivors receive a final verdict about the plane crash. Meanwhile, Derek continues to undergo rehabilitation on his hand, Cristina and Owen enjoy their new relationship with each other and Richard tried to avoid Catherine's advances.
Arizona is grappling with the pain of Phantom Limb when a consultant arrives at the hospital to begin investigations. While Derek embarks on his first major surgery, Meredith faces her biggest fear as she experiences pregnancy mood swings.
While Derek and April try and find a way to save the ER, Cristina and Leah struggle to keep a patient alive while respecting his wishes. Alana is pulled into a surgery with Owen that may change the way she views the hospital's ER.
Alex and Jackson are pitted against each other to become the next "face" of Seattle Grace while they work on a sex reassignment surgery for a trans-gender teen. Then, April brings in an emergency trauma case which requires the help and discretion of many of the doctors. Meanwhile, Callie and Richard visit a recently revitalized hospital to understand what they are all in for.
As the hospital inches closer to finding a buyer, many of the doctors don't like the new changes being made, causing the crash survivors to consider a crazy idea. Meanwhile, April's relationship with Matthew progresses and she asks Jackson for advice.
The crash survivors race against the clock to find a buyer for the hospital before Pegasus closes in. Meanwhile, the interns and other doctors at SGMW plan for what they believe will be their imminent departure while Jackson's mother continues to try to convince him to move to Boston.
With the new Grey Sloan Memorial Hospital up and running smoothly, everyone is happy about the new changes. Meredith worries about the health of her baby while Bailey tries to get the board members to fund her new plan for genome mapping. Meanwhile, Arizona's new prosthetic gives her the confidence to reignite her relationship with Callie. With the help of a patient, Alex pulls some pranks on Jo's new boyfriend and Cristina tries to get involved in groundbreaking cardio research.
When a giant gas tanker explodes on a highway, a couple of parents are admitted to the hospital while Owen looks after their son. Matthew is caught in the explosion and is admitted to the hospital while a single mother fights to find out what mysterious illness is plaguing her son.
A couple of Syrian doctors arrive at Grey Sloan Memorial to learn field techniques for war zones. Then, when a series of patients return with post-op infections, one doctor's work falls under suspicion.
At Jackson's request, the CDC arrives at the hospital to begin an investigation surrounding Bailey's patients. April blames Jackson for her breakup with Matthew and Alex tries to be nice to Jason. Owen continues to get closer to Ethan as his dad's health remains uncertain.
A magician's assistant arrives at the hospital with a severe injury that has all the general surgeons involved, except for Bailey who is ignoring all of the attendings. As Cristina searches for a way to wake his father up, Ethan has a medical emergency of his own. Alex tries to avoid Jo at the hospital and a new cranial-facial specialist flirts with Arizona.
With a major storm rolling in, the hospital is chaotic. When Jason comes into the hospital in critical condition, Alex does everything he can to protect Jo. With Meredith's due date just weeks away, Derek urges her to slow down.
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.
Ben worries that an innocent conversation with Derek could end up causing problems for Bailey; Cristina turns to Shane as tension with Meredith increases; April's upcoming wedding creates an uncomfortable situation for Stephanie and Jackson.