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).

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.

A former patient of Link’s, Simon, is in the ER with his pregnant wife; and Bailey receives an offer from Nick.

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.

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.

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.

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.

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.

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.

Bailey tells the interns they must complete dozens of basic procedures before being allowed back in surgery; things are awkward between Simone and Lucas; Amelia comes up with a solution to a complicated surgery.