Severide stops by Casey's house to apologize for Benny's behavior the day before. While he's standing at the door, he notices Heather inside. Casey doesn't have time to explain that Heather slept on the couch before Severide drives away in a huff.
Later, the squad is going through the arduous process of flushing fire hydrants. A neighborhood kid calls the firemen to his apartment complex, where they find his brother stuck in an old laundry shoot. The squad members quickly grab their gear and cut the boy out of the wall. He's alive, but badly hurt.
Back at the station, Mouch shows off his Japanese skills to win a bet with Otis. Severide tells Casey that he's planning to transfer Mills to squad. Casey is upset that nobody consulted him about the transfer. At the hospital, Dawson tries to comfort the mother of the boy stuck in the laundry chute. The boy's mother tells Dawson that her son idolizes firefighters.
Chief Boden calls Mills into his office and tells him that he doesn't think Mills is cut out for squad. Shay asks Severide if he'll donate sperm so that she can have a baby, but Severide doesn't answer her. In the loading dock, Severide attempts to confront Casey about his involvement with Heather, but the conversation is interrupted when a drive-by shooter opens fire on the station, shattering windows and forcing everyone to hit the deck.
After some interviews, the police head out to search for leads. In the meantime, they post police officers outside the station. The next morning, the gang presence around the station seems more noticeable. Later, Severide tells Shay that he'll donate his sperm so that she can have a baby, and she is overjoyed. Dawson intercepts Mills on a jog and convinces him to talk to her about his problems.
The team returns for their next shift to discover that the boy trapped in the laundry shoot died in the hospital. Shay and Dawson respond to a paramedic call. While they attend to a homeless man, their ambulance is stolen with Dawson in the back.
The police immediately give chase, while Dawson holds on for dear life in the back of the ambulance. Dawson thinks fast and tricks the thief into stopping the ambulance. Later, Shay tells Severide that she can't afford the costly lab fees for insemination, so she'd like to do it "the old-fashioned way." Severide agrees to the proposal.
Casey confronts the gangbangers on the corner and convinces them to take him to their leader. When they oblige, Casey talks to the gang leader. He discovers that the gangs hide their drugs in fire hydrants, and they're upset because the squad flushed their stashes. Casey tells the gang leader to stay away from the hydrants.
Back at the station, Shay tells Severide that her father agreed to pay for the insemination. Later, the firefighters assemble outside to pay their respects to the funeral procession for the boy trapped in the laundry chute. The gangbangers witness the show of respect and decide to stop harassing the firehouse.