The attending surgeons and interns work together to solve a medical mystery when a college kid comes in with what first looks like food poisoning but has escalating and dire complications. Meanwhile, Jo spends her day off with Bailey.

Bailey recruits the interns to create a series of social media videos informing teens about sexual health. The videos, filmed at Grey Sloan in front of a group of high schoolers, hit home as a student has medical complications during her visit. Elsewhere, Meredith and Maggie learn something new about Zola.

It’s Halloween night at Grey Sloan Memorial. Meredith and Nick try to spend some alone time together; Levi is stressed due to overworking, and Winston and Owen have the interns practice trauma training on a real cadaver.

Bailey and Addison take a road trip to volunteer at a family planning center, but a patient’s ectopic pregnancy leads to complications. Elsewhere, the interns play detective about Lucas’ relationship with Amelia, and Meredith catches up with Jackson on a trip to Boston.

On the heels of life-changing news, a thunderstorm hits Grey Sloan. The attending surgeons and interns work together to save an injured reporter and family affected by the storm. Meanwhile, a beloved author undergoes a risky surgery, and complications from the storm arise.

It’s Meredith’s last day at Grey Sloan Memorial and the doctors plan a goodbye surprise, while Nick confronts her about the future of their relationship. Elsewhere, the interns compete to scrub in on Maggie and Winston’s groundbreaking partial heart transplant procedure, and Richard asks Teddy an important question.

Teddy makes a challenging decision. Meanwhile, Maggie and Winston aren’t on speaking terms, and Link leans on Jo for emotional support as he preps for a surgery on a well-known athlete. Simone and Lucas are surprised by an unlikely visitor.

Simone is met with a life-changing decision upon the return of someone from her past. Blue shadows Maggie on a risky procedure, while Jo and Link tend to a pregnant woman. At the intern house, Lucas and Mika throw a party filled with surprises.

Catherine returns to Grey Sloan for a surgical case that makes Lucas and Blue queasy. Amelia treats a possible cancer patient with a family that’s a little too supportive. Owen takes his medical future into his own hands, much to Teddy’s surprise.

Addison makes a special appearance at Grey Sloan to welcome Bailey’s new OB/GYN trainees. Maggie’s lung transplant is derailed, and Nick bonds with Lucas — before the day takes a shocking turn.

In the immediate aftermath of shocking events at the clinic, the hospital goes on lockdown and the Grey Sloan doctors split up to save multiple lives; Maggie lands in hot water with Winston; Jules' roommate makes a surprise appearance.

A bull rider shows up at Grey Sloan with severe injuries, forcing Maggie, Amelia, Owen and Blue to examine their own biases. Elsewhere, Simone can’t find anyone to be her maid of honor, and Mika takes drastic measures to pay down her student debt.

It’s Maggie’s last day. Amelia’s relationship with Kai is tested, and Ben worries as Bailey’s doxing intensifies.

With Levi’s help, a patient celebrates a milestone. Jo processes a difficult diagnosis, and Maggie and Winston decide their future.

Amelia takes her personal problems out on her work colleagues, and the threats against Bailey come to a terrifying head. Lucas and Jules make a risky decision on a patient, and Mika struggles with burnout.

Teddy calls an emergency meeting to discuss the intern program. Link wrestles with his own self-doubt as he preps for a massive surgery, and Nick shares some much-needed guidance with a struggling Lucas.

Richard and Teddy make an exciting announcement. Jules and Blue butt heads over Maxine’s care while Lucas helps an artist decide on a risky procedure. Jo and Mika tend to Sam as Simone faces a life-changing decision.

Simone's wedding day arrives as Jo and Link's relationship hits a major turning point.

The attending surgeons fly to Boston, forcing a reunion between Nick and Meredith. Bailey gets a big surprise.