Relationships are challenged at Station 19 following Sullivan's actions at Maya and Carina's wedding, putting his marriage with Andy to the test. Dean comes to terms with his feelings for Vic, while Travis rekindles an old flame. The annual Phoenix Festival brings out some reckless behavior in some of Seattle's citizens, challenging the teams at Station 19 and Grey Sloan Memorial.
When a heat wave hits Seattle, Station 19 becomes a cooling center and chaos ensues with locals who aren't used to the extreme temperatures. Andy deals with regret and finds a friend in Theo. Joey comes face-to-face with his past during a ride-along with Ben and Jack
Diane returns to help with Crisis One intervention training for Station 19 and Station 23 firefighters. Meanwhile, Andy and Sullivan continue to be at odds, and Jack helps a young autistic man on a city bus.