Andy, Jack and 18 other candidates take the captaincy drill test, gunning for one spot as captain of Station 19. Meanwhile, Travis is serving as acting captain while Andy and Jack are away for the day; and Ben confronts Vic about her fears.

Ryan tags along to a disaster drill training at Station 19 where he and Jack get competitive. Captain Pruitt’s health weakens and Andy is sticking by his side. Meanwhile, both the firehouse crew and police department respond to a strip mall fire, forcing Jack and Ryan to work together.

Ripley interviews each member of the Station 19 crew to determine whether Andy or Jack should be given the role of captain. Meanwhile, a mom’s day out on a party bus takes a turn for the worst; and Captain Pruitt continues his treatment.

Ben reaches a new milestone as a rookie and, as is tradition, receives something from the crew. Chief Ripley holds final interviews for the role of captain but is interrupted when the team is called to a massive skyscraper fire, causing several lives to hang in the balance.

Lives hang in the balance as the members of Station 19 continue to fight a raging inferno inside a skyscraper. Meanwhile, Pruitt’s health is in grave danger at Grey Sloan; and a seasoned firefighter with a mysterious past arrives at Station 19, leaving everyone to wonder what the future holds.

Everyone is less than enthusiastic when Sullivan assigns each member of the crew a specialty skill to learn. During a house call, Ryan is caught off guard when he comes face-to-face with someone from his past; and Sullivan, Andy and Maya handle a structure fire in a derelict building.

Captain Sullivan continues his efforts to bring together the fire and police departments by hosting a training seminar that does not go as planned. Meanwhile, Ben and Miranda have an honest conversation about their marriage, leading Miranda to make a tough decision about their future.

As the team gathers for a Friendsgiving celebration at Dean’s, a violent windstorm touches down in Seattle. As the storm picks up speed, creating dangerous fire conditions, the crew must put the festivities on hold and report for duty, leaving some of them in a life-threatening situation.

In the aftermath of the windstorm, Andy and Sullivan’s fates remain unknown while trapped in the overturned aid car. Meanwhile, back at the station, the team confronts Jack about his well-being; and when it’s safe enough to venture out, they search for their fellow firefighters in a race against time.

When Andy, Maya and Dean respond to a call, they find an injured woman with amnesia; but soon into the treatment process, they realize there is much more to her story. Meanwhile, Captain Sullivan takes Ben and Jack on a house call that quickly becomes a close call for the patient they’re treating, while Ryan may not have seen the last of his father, Greg.

When an RV crashes into Station 19, the team races against the clock to save lives and secure the building’s compromised structure. Meanwhile, a surprise delivery arrives at reception.

While struggling to help victims of a crash on a desolate road, Vic finds the courage to confront a difficult situation. Meanwhile, Ben prepares to go out for Medic One, causing some concern over his current Station 19 responsibilities, and Pruitt spends time with a special someone.

A blackout in Seattle creates dangerous situations throughout the city and the members of Station 19 head out on calls, including locating a missing girl and helping a man on life support where every second counts.

When Station 19 gets called to a structure fire at a coffee processing plant, the team risks their lives to save Station 42’s captain. Meanwhile, Ripley and Vic consider a shocking option to save their relationship; Andy gets some surprising news about some of her fellow crew members, and Pruitt takes on a new position.

Following a deadly blaze inside a coffee beanery, the members of Station 19 find themselves on high alert as a beloved member of their team lands at Grey Sloan, leaving the future uncertain in the face of a life-threatening situation.

The crossover starts on Grey's Anatomy S15E23 What I Did for Love (I)

As Ben readies the new Physician Response Team truck for the field, his suspicions about Sullivan and the missing Fentanyl continue to grow. Meanwhile, Jack and Rigo try to look past their differences when they are forced to work together and fight a mysterious gas station fire; Dean and JJ try to work through their differing parenting styles; and Travis meets someone new.