A gas tanker explodes on a Seattle highway, causing multiple injuries, including paramedic Matthew. Meredith and Jo help a frantic mother whose child is suffering from a mysterious illness. Owen bonds with a young boy whose parents are in critical condition. Meanwhile true colors are revealed when Alex is forced to work with Jo's boyfriend on an ailing patient.

Upon receiving some unsettling news, Meredith and Derek take preventative steps for their children’s future; a group of Syrian doctors arrive at Grey Sloan Memorial Hospital for a crash course in basic surgical skills that they plan to apply in the field; and April decides to come clean to Matthew regarding the truth about her virginity. Meanwhile, multiple pre-op patients develop infections, causing one doctor to wonder if she is at fault.

Bailey finds herself at the center of a CDC investigation surrounding the death of several of her patients, as Jackson and the rest of the board members argue over how to address the crisis with the public. Meanwhile, Cristina teases Alex about his unspoken feelings for Jo, and Owen continues to take special care of Ethan as the condition of his parents remains uncertain.

The doctors reach out to Bailey but she continues to shut everyone out; after an incident with Ethan's grandmother, Owen fears the child could end up in foster care. A new craniofacial specialist arrives at Grey Sloan Memorial Hospital to work on a young patient. Meanwhile, a magician's assistant is rushed into the ER after a magic trick goes terribly wrong.

The doctors of Grey Sloan Memorial Hospital prepare for a super storm heading towards Seattle. Owen's desire to be a parent gets stronger as he becomes closer to Ethan. One wrong move puts the lives of Meredith and her baby in jeopardy. Meanwhile, Jo looks to Alex for help in a moment of crisis, and one doctor gets the shock of her life.

Grey Sloan Memorial Hospital enters crisis mode as the storm rages, resources become scarce and patients flood in by the busload. Meanwhile, one of the doctors fights for their life.