Meredith and Catherine continue to disagree, and Meredith confides in Bailey for support. Richard, Winston and Lucas spend the day outside of the hospital, and Blue deals with a relationship from his past. Levi meets the new hospital chaplain.

In the midst of a deadly heat wave, the team at Grey Sloan struggles to keep up with an overwhelming amount of patients. Amelia and Winston face a challenging surgery, while Jo and Lucas run an errand for the hospital that takes an unexpected turn.

The aftermath of the convenience store shooting brings chaos to Grey Sloan. Ben hits a wall with his new emergency preparedness plan. Romantic tensions surface for Owen, while Amelia and Winston disagree over the surgical plan for a young patient.

Amelia and Simone attempt to perform a high-stakes and groundbreaking brain surgery. Teddy and Bailey attend a medical conference and run into Dr. Cass Beckman. Meanwhile, Jo struggles with her irritation toward a younger OB-GYN.

Jo and Link's wedding day arrives, along with some visitors. Meanwhile, Teddy and Owen are met with a familiar face seeking treatment, and Lucas disagrees with Simone on how to approach a patient's worsened condition.

While the interns are excited to transition to second-year residency, an ordinary day at Grey Sloan takes an unexpected turn when a medical emergency unfolds in the operating room, endangering lives inside the hospital.