It is 6 months later. Herrera teaches a self defense class. Bishop and DeLuca are still trying to get pregnant. Gibson is trying to find his foster sister. Station 19 is called to a car crash and upon arrival, they notice an incoming tornado. Montgomery goes to a meet the candidates event. After the tornado threat passes, the team returns to the car crash only to discover that one of the cars, inside which a woman was wedged, is missing. The car ends up at the meet the candidates event and Montgomery rescues her from the car. Station 19 is then called to a house that turns out to be where Eva Vasquez lives and they find out that's where Gibson has been for the past 3 months. DeLuca finds out that Bishop blackmailed Chief Ross and they fight about it.

Herrera learns about Bishop's blackmailing. Gibson comes to the hospital where DeLuca takes care of his injury. The team is called to a building fire, but the hydrant is dry, so they drain the pool to get water. Gibson reveals to DeLuca that he indeed left to find his sibling and met with his brother Cal, but his brother did not remember him. Herrera makes up a story about the blackmailing to tell the rest of the team to cover for Bishop. Bishop tries to make amends with Beckett by giving him alcohol.

Crisis One gets called to a potential domestic abuse, which turns out to be at the Dixon's house. Station 19 is called to a fire of an electric car. Vic persuades DeLuca to take a pregnancy test. Gibson fights with Eva.

The station is getting ready for Halloween. Sullivan meets Ross again. A man, Eli Stern, stops by station 19 to talk about Montgomery's campaign. Gibson starts having hallucinations involving Rigo Vasquez. Eva breaks up with Gibson. Aid Car is called to a fair, where a fire starts in the corn maze. Station 19 is holding a Halloween event for children and Gibson stops by.

Bishop and DeLuca finally make up. Hughes tries to spread the word about the girls fire camp. Information about Montgomery's intoxicated assault resurfaces, just before his union board meeting. Crisis One is called to a man who plans to die by suicide. Gibson comes to the Memorial Clinic. Station 19 is called to a factory with several people locked in a seal-tight chamber. A mysterious woman stalks Gibson while at the Clinic and hands DeLuca a file to give to Gibson. The man at the Crisis One call turns out to be the only person capable of opening the chamber. Gibson reveals the file is from his biological sister.

DeLuca admits to Bishop that she took a pregnancy test alone. Stern is now running Montgomery's campaign instead of Hughes. The station is starting their girls fire camp. Gibson stops by the station and Ross forces him to volunteer for the camp. Station 19 is called to a helicopter crash. Chief Ross is asking for opinions of Captain Beckett. While rescuing a man from the helicopter, the team revolts against Beckett, who makes Herrera the captain for the mission. Gibson tells Hughes about his sister. A man arrives to the station with several people struck by lightning in his car. Hughes asks the girls from girl camp to help with CPR. Ross asks Hughes to run Crisis One. Ross breaks things off with Sullivan. Bishop is getting increasingly more injured which impacts her work performance.

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This episode begins a crossover event that concludes on Grey's Anatomy season 19 episode 6.

The team fights a fire at Dr. Meredith Grey's house. Jack finds Maya injured at the station and takes her to Grey Sloan. Later, Andy and Vic are called to sedate a man who is resisting arrest by the police. They realize that the man does not understand the officers and declare it a Crisis One call. Both Ross and Dixon are called, and the circumstances escalate until Ross is able calm the situation and takes the man home. Sullivan tells Ross that he is willing to wait for her so that she can put her career first. Carina wants Maya to recover from her injuries and commits her to force treatment.

Bishop is having therapy with Dr. Diane Lewis. She has a breakthrough when she realizes that she has a need to win to avoid disappointing her father. Gibson is back on the team to fill in for Bishop. The firefighters receive a call to Ruiz's old neighborhood. When a woman rushes back into a burning house, Ruiz goes against orders and goes after her. Beckett benches Ruiz for disobeying. Hughes is worried that Ruiz could have died like Ripley did. Dixon is trying to use the previous incident with Ross, involving a possible police civil rights violation, to boost his mayoral campaign. At the press conference, Ross credits Crisis One instead and invites officers to receive the training. Herrera wants Beckett to improve his leadership, but it is revealed that Beckett continues to drink on the job.

At the Memorial Clinic, DeLuca flirts with a pregnant woman that she is treating, and Gibson notices. Sullivan is treating a drunk man that Beckett wants to send to a hospital. It is revealed that the man is Beckett's uncle. Ruiz and Hughes are performing a fire inspection at a barbershop in Theo's old neighborhood. Hughes points out electrical violations, but Ruiz ignores her. When the power goes out, Hughes argues with Ruiz about how he acts differently in the old neighborhood, and he apologizes. Eli rides along with Herrera and Montgomery to get campaign footage and ends up injured. Eli asks Herrera out on a date, and she accepts. Bishop contacts DeLuca, but Carina needs more time apart.

Stations 19 and 88 are running a training exercise led by Beckett. Cooper, from Station 88, used to serve under Beckett and calls him a great captain. An accident occurs during the exercise, and Copper is injured and later dies. Ruiz asserts that Beckett's drinking led to Cooper's death. Meanwhile, Gibson's biological sister, Brooke, and her friend come to the station injured after driving while intoxicated. Gibson disapproves, which upsets Brooke. However, after her friend loses consciousness and is sent to the hospital, they forgive each other. Montgomery is conducting radio interviews with Eli from Herrera's apartment. He excels after learning to speak from the heart instead of from a script. Eli later comes to the station to return Herrera's keys, and they kiss. Bishop makes a lasagna for DeLuca, who ends up with food poisoning, so Maya goes to take care of her.

The team gets a call for a fire at the barbershop in Ruiz's old neighborhood. Fearing Beckett's mental state, the team decides to ignore him and lets Herrera take command of the situation. Beckett chooses to run into the shop to rescue a man and nearly dies. Meanwhile, Hughes and Dr. Diane Lewis are meeting for Crisis One, and DeLuca comes to see Bishop. A car comes into the station with a dead deer in the windshield, and the three rescue the woman inside. After hearing the woman's story, DeLuca worries she will be hurt if she stays with Bishop. Maya confesses to Warren that she gave alcohol to Beckett. Ross makes sure that the investigation into Beckett's involvement in the training accident is impartial. Beckett announces that he is taking a leave of absence.

Ross is reprimanding the team when they get a call about a man and woman who fell inside a cave. Ross takes command, and Montgomery and Bishop repel down to rescue them. Bishop hears over the radio that an incident has occurred at Grey Sloan. The woman, who is live-streaming the whole time, is rescued by Montgomery, which give him more publicity. At the station, Warren treats a man who was bitten by a black widow spider, and he tells Ben about the riot at Grey Sloan. Ruiz and Hughes perform an informal arson investigation at the barbershop, and they ask the officials to look into similar incidents in the neighborhood. Ross wants Herrera to be acting captain, but Andy declines and recommends Sullivan. Instead, Ross names Ruiz acting captain. Bishop and Warren rush to Grey Sloan to check on their spouses.

The firefighters are called to a house being demolished. Two brothers are fighting inside, putting Gibson and Hughes in danger. Ruiz is micro-managing the situation, and Hughes does not have time to update him. Sullivan offers a solution, which goes against protocol, but everyone is saved after Ruiz relents. Ruiz and Hughes argue about their inability to communicate. Meanwhile, Bailey, DeLuca, and Warren are at a crisis pregnancy center with Carina posing as a pregnant woman. They are trying to obtain evidence that the people working there are not medical professionals. They are discovered, but see protestors outside the building who share their view. Montgomery is at a debate when he notices an exposed cable. He tapes the cable in front of the audience and uses it as a metaphor for how he will fix the city as mayor. Eli and Montgomery celebrate his performance and end up having sex. Dixon shows Bishop photos of Sullivan and Ross in bed together.

The team is making dinner to celebrate Ruiz's captaincy when they are called, and Gibson accidentally leaves a burner on. When they return, the sprinklers have ruined the food. Ruiz accuses Herrera of undermining him, but she tells him that she had previously declined the offer to be captain. Ross learns that Sullivan is considering a position in another city because he was passed over for captain. Warren and Bishop are called to rescue a trapped pregnant woman, who previously flirted with DeLuca. Carina is called when she needs to deliver the baby. Montgomery is anxious when he finds that he could realistically become mayor. He decides to drop out and endorse another progressive candidate, which angers Eli. Herrera finds out that Montgomery and Eli slept together, and Travis learns that Eli and Andy kissed. Bishop tells DeLuca and Herrera about the photos of Ross and Sullivan. Gibson helps four boys after they get sick due to ingesting spicy chips.

Herrera and Bishop show Ross the photos of her and Sullivan. Dixon wants Ross's endorsement in exchange for his silence about the photos. Ross goes to the firefighters union and admits her relationship with Sullivan. Bishop and DeLuca treat an injured woman while they are on a date. The team is called to a fire at an overcrowded clean-living house. Warren falls through the roof while inspecting it and breaks his arm. He finds two men trapped in the house, but he can only carry one of them out before Ruiz calls a retreat. A firefighter named Kate Powell, who knows Ruiz, substitutes for Warren while he is injured.

The mayor has called on Ross to resign, which she plans to do. Herrera convinces her to fight for her position to keep her legacy intact. Warren continues to feel guilty for not saving a man who was trapped in the fire on the previous episode. His friend, whom he saved, is in the hospital, and Warren stays by his bedside. When he wakes up, he angrily kicks out Warren, and Ben has a breakdown. Beckett returns to the station on probation. He apologizes to the team and confesses that he feels guilty that he may have caused his friend's death. He announces that he would not be seeking his captaincy back, and his behavior worries Hughes. At the scene of a multi vehicle accident, jealousy and resentments flare up.

It is election day, and the station is serving as a ballot drop-off location. Eli and Dixon appear to make sure things are running smoothly. Montgomery apologizes to Eli for dropping out of the race. Ross announces that Warren will be awarded a Medal of Valor for saving a man while injured, but he does not want it. Herrera, Sullivan, and Ruiz have applied to be the permanent captain for Station 19. On a call, the three fight to stand out so they can make the best case. Meanwhile, Beckett has called in sick, and Hughes lies to Ruiz so that she can check on him. She is badgering him with questions because she is worried that Beckett will commit suicide. After the two share their losses while on the job, Beckett has a breakdown, and he decides to return to rehab. Meanwhile, the rest of the team responds to a car wash call and Herrera goes against Ruiz and after the team has an argument, Ross says she might have to rethink things. After Beckett leaves, Hughes has her own breakdown after he leaves. Dixon loses the election, and Eli accepts Montgomery's apology. Gibson meets with his biological sister, who has found his foster sister. When DeLuca learns that Bishop did not apply to be captain so she could put her marriage first, she decides to move back in with Maya.

The team attends the Firefighters Ball where Warren will receive his Medal of Valor. After some encouragement from Miranda, Warren accepts the award in honor of those who could not be saved. Dixon is there because his wife oversees the ball. Gibson notices a pregnant waitress named Nanette. Ross privately tells Herrera that she will be named captain. The news leaks out, and Hughes wants to celebrate, which upsets Ruiz. At first, Bailey says the situation in the back kitchen is under control but no one knows for sure. At the ball, Ruiz and Hughes argue about their relationship. Later, Gibson catches Ruiz kissing Kate Powell. When smoke comes out of a wall, Ross has Herrera take command to find the source. She extinguishes the fire in the basement but notices that the floor above is about to collapse. She tries to warn the guests, but people, including Ross, Dixon, and Nanette, fall into the hole. Bishop and DeLuca find Nanette and perform an emergency delivery of her baby. Sullivan finds and revives Ross, and they make up. Montgomery finds Dixon and tries performing CPR on Dixon, but he succumbs to his injuries and dies. The situation gets under control when, suddenly, Gibson collapses.