Meredith seeks advice from Amelia. Meanwhile, Richard is reenergized as he takes teaching to a new level at the hospital, and Winston treats a patient suffering from kidney failure.

Seattle’s favorite redhead returns and graces the Grey Sloan halls with her experience and expertise as she attempts to help Richard teach the newest crop of residents. Meanwhile, Meredith has a decision to make, and Link confides in Teddy.

The Grey Sloan doctors spring into action after an explosion rocks Seattle, with the incoming trauma hitting close to home. Owen experiences PTSD after he hears the explosion, while his sister Megan enlists help from Winston and Hayes in confidence. In Minnesota, Meredith and Amelia meet up with a familiar face who assists in their study.

The crossover starts on Station 19 S05E05 Things We Lost in the Fire (I).

Dr. Hamilton takes his frustrations out on Meredith, so Nick gives her a chance to blow off steam by scrubbing in on a surgery. Back in Seattle, Link and Jo take their kids to a fairytale theater performance that goes wrong. Bailey and Dr. Lin attend a recruitment fair in hopes of attracting more doctors to Grey Sloan but find themselves ill-prepared.

The doctors celebrate the holidays; Hamilton and Meredith prepare for a milestone on their project; Link wants to spend the holiday with Amelia and Scout as a family; Schmitt is faced with a difficult decision during surgery.

The Grey Sloan Memorial doctors grapple with the aftermath of the car crash that involved some of their own; Meredith works to save Dr. Hamilton's life. Levi is impacted from his latest loss.

While Meredith, Amelia and the team prepare for Dr. Hamilton’s long-awaited, groundbreaking surgery, Bailey receives an unexpected offer. Owen’s impatience makes him a difficult physical therapy patient, forcing Link to intervene. In Minnesota, Nick makes a liver transplant a teaching moment.

Nick whisks Meredith away to his Minnesota cabin for a romantic weekend, leaving Winston and Maggie to care for Meredith’s children. Meanwhile, Amelia and Kai grow closer.

While Richard ponders his surgical abilities, Jo is charmed by her patient’s brother. Elsewhere, Megan makes sure Teddy and Owen talk out their differences, and a pet python causes an uproar.

Bailey is on edge when an accreditation council stops by Grey Sloan to review the residency program, while Richard sets an assessment of his own for the same day. Meanwhile, Nick returns to Seattle to perform a first-of-its-kind operation with Meredith.

A dinner party is thrown at the sister house in Nick's honor. Meanwhile, Grey Sloan Memorial receives a victim of a brutal hate crime.

The blood shortage at Grey Sloan Memorial continues. Meanwhile, Meredith makes a risky decision regarding a patient, and Owen’s actions to help his fellow veterans come to light.

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.

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.

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.

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.