Firehouse 51 is out of commission when a local turf war is going on in their back yard. After Gabby and Sylvie are called out for a GSW, Matt and Stella are the first hear gunshots nearby. Before they can lock down the house, a group of about 10 young men forces their way in and holds the house at gunpoint. Stella is tasked with treating their injured friend, and she manages to let Kelly, who was in the showers when the house was over run, know what is going on. Kelly then sneaks his way to the squad truck, where he gets word out to central dispatch. Unfortunately, dispatch isn't able to warn Ambo 61 in time, and the roll up just as the leader was considering leaving. Matt rushes to warn her away, and is shot in the shoulder, and the situation escalates as the cops arrive on the scene. Stella has bonded with the young man, JB, who was guarding her as she worked on his friend. Another ganag member, Marvin, is recruited to help when the friend starts doing poorly, and he doesn't take to her quite as well. He threatens her in the locker room, and she responds by punching him. He knocks her out cold in retaliation. The gang wants to use a fire truck to escape the situation and ram past the police. Hermann fakes a heart attack so he will be released, and lets the cops know what's going on inside. Sylvie recruits JB's mother into making a plea for him to give himself up. The leader urges him not to listen. JB agrees to go along with the escape plan, but once in the truck he signals to Boden that he's willing to help him. They work together to disarm Turk, but the bullet ricochets and hits JB in the neck. Things don't look good at first, but Gabby and Sylvie are able to save him.