Link tries to convince Amelia to take it easy during the final stage of her pregnancy. Hayes asks Meredith a surprising question, and Owen makes a shocking discovery.

Owen and Link treat an older woman who wakes up from surgery and can't stop singing, while Teddy helps Koracick stay afloat after an estranged loved one from his past comes to the hospital looking for help. Meredith, Bailey and Maggie focus their efforts on a difficult patient with a tricky diagnosis. 

Richard preps to present his PATH pen at the LA Surgical Innovation Conference but becomes distracted by his issues with Catherine. Maggie and Teddy run into people from their past at the same conference, while Hayes relives moments from when he met his late wife.

Meredith heads up a pro bono surgery day, but the overwhelming patient response causes her to struggle to keep things in order. DeLuca treats a teenage patient whom he suspects is in danger and desperately tries to get Bailey to support his theory.

A wealthy inventor arrives at Grey Sloan and asks Koracick for help, while Meredith struggles to save a woman with diabetes who has been rationing her insulin. Jo and Link fight to save a young man who fell onto train tracks, and Jackson and Vic's relationship hits a snag.

Bailey and Ben face a huge, life-altering decision; Meredith and several of the doctors reflect on the past.

Meredith and Carina question DeLuca's uncharacteristic behavior when he volunteers to perform a life-threatening task during a blizzard. Meanwhile, Bailey tries to help Joey with his future, while Richard trains a new intern at the hospital.

DeLuca is irritated after Meredith takes over his patient Suzanne whose symptoms continue to stump the doctors at Grey Sloan. Elsewhere in the hospital, Jackson, Owen and Jo work on a couple injured in a bear attack; and Levi is hurt when Nico doesn't want him to meet his parents.

DeLuca can't figure out what's going on with his incurable patient Suzanne and he turns to a diagnostics genius, Dr. Riley from UCSF, for help. Bailey checks in on Joey, a foster kid that Ben brought into Grey Sloan. Meanwhile, Amelia is getting the results of her paternity test and Jo confronts her about how she is treating Link.

Jackson creates an uncomfortable situation when he invites new girlfriend, Vic, to what he thinks is Richard and Catherine's anniversary celebration, only to discover the dinner was called for different reasons. Elsewhere, Levi brings Nico on a trip to visit an ailing family member. 

Richard finds out Maggie quit Grey Sloan and is concerned about how she's handling the death of her patient who was her estranged cousin. Bailey returns to work after taking some personal time off, although Koracick doesn't make her first day as easy as she'd like. Meanwhile, Meredith thinks she might miss DeLuca, and Amelia has an update for Link on her pregnancy.

Second part of a crossover that started out on Station 19's third season premiere.

Jo becomes a safe haven volunteer and gets a call that a baby has been dropped off at Station 19. Meanwhile, Meredith moves forward with her life after facing the medical board. Jackson takes a big step in his budding romance with Vic, while Bailey and Amelia swap pregnancy updates.

Meredith faces the medical board as her future as a doctor remains uncertain, and she's forced to reckon with her past in some challenging ways. Meanwhile, the interns are put to the test as they are each vying to be the most successful on their respective cases in the absence of some of the attendings.

Catherine is back in town and has no idea what's been going on between Jackson and Maggie, while her relationship with Richard has become distant. Owen and Amelia treat a woman who fell in the basement and quickly realize that there is more to the story; and Maggie is shocked to learn about some of Richard's relatives who are seeking help.

Alex is hoping to impress investors at Pac-Gen North, but when he hears disturbing news about skeletons on the construction site grounds, he enlists Richard to help with distraction tactics. Teddy feels the pressure to be super-mom after tasking herself with creating original Halloween costumes for Allison and Leo, while Meredith fears she won't make it home in time for trick-or-treating with her kids. Elsewhere, Jackson tends to a pediatric patient who is upset she is spending her Halloween in a hospital.

Meredith has a court hearing after skipping out on community service, while Bailey and Jo have a patient that Jo realizes is from the treatment facility. Richard and Gemma grab breakfast together and things go awry.

After Meredith inadvertently stirs up negative press for Grey Sloan, she tries to make things right with her former colleagues, jeopardizing her community service hours. Station 19's Ben and Vic bring a young woman into the hospital, and Jackson stands up to Koracick when he goes too far with a patient's family. Meanwhile, Bailey receives unexpected news; and Owen finds himself at Pac-Gen North, which Alex sees as a recruiting opportunity.

With new restrictions, Meredith tiptoes the line of protocol as she helps Jo with a difficult procedure from afar; and Koracick makes things challenging for Owen at Grey Sloan. Meanwhile, a patient at the hospital is brain-dead after falling into a construction site, and her two sisters must decide whether or not to keep her alive.

The Grey Sloan doctors operate on a man who crashed into Maggie's car as Owen, back from paternity leave, struggles with Tom's new position. Outside the hospital, Meredith's recent firing doesn't stop her from diagnosing those around her. Plus, Richard and Alex start anew and it's not easy. All the while, Jo readies herself to return to work, and Amelia has a new revelation in her relationship with Link.

Meredith, Richard and Alex must deal with the consequences after Bailey fires them from Grey Sloan for insurance fraud. After disappearing in the fog, Jackson helps a man in a dangerous situation, as his relationship with Maggie comes to a new crossroad. Meanwhile, Tom gets new responsibilities at the hospital that throw the doctors for a loop.