|Season 3, Episode 8|
"Nobody Touches Anything"
"Arrest in Transit"
Chief Boden and Donna visit the doctor together for an ultrasound and revel in seeing their baby on screen for the first time. However, the checkup takes a tough turn when the doctor reveals that Donna may suffer from placenta previa, a condition that puts her at high risk for a life-threatening hemorrhage in her third trimester. They struggle with the news, but some good comes with the unknown: Donna decides to ask about the sex of the baby, and it's a boy. Boden beams.
Later, a call sends the whole team out to a scary crash where a helicopter teeters on the roof of a building, still smoking. Severide finds the pilot and two passengers still inside and rushes to save all three as pieces of the roof crumble to the ground. He barely emerges with his life - a fact not lost Brittany who arrives on the scene, terrified for her new husband's safety. Her worried presence at the scene frustrates Severide and the two fight afterwards - until Brittany reveals that the chopper catastrophe reminded her of a fatal crash from her past. They appear to reach an understanding, but the question lingers: can Brittany handle Severide's job of running headfirst into danger?
Across from the rooftop disaster, Otis and Herrmann locate the helicopter rotor in a nearby backyard - and find a woman pinned underneath it. Herrmann attempts to keep the victim calm as Otis slowly dismantles the rotor in order to lift it off of her. When they manage to save her, Otis makes a new discovery - a damaged remote control drone, the cause of the crash. Dawson confirms the connection when she follows a small blood trail to a shed, where a bludgeoned kid confesses to flying the drone with his brother. Casey and Cruz find his brother barely conscious and surrounded by live wires in a transformer cage, having fallen off the roof after the helicopter clipped him. They disentangle the kid and pull him out, making a narrow escape before the live wire touches the boy's blood.
Brett and Mills locate another massive piece of the copter on top of a van with an injured driver inside. But the driver refuses to cooperate, an issue that confounds Brett until she spots a bag full of passports and licenses. She soldiers on and patches him up, even after he reveals a gun and then rejects further treatment. The next day, he tails Brett and corners her in alley. Instead of confronting her, he apologizes and hands her a business card: she can contact him for anything, anytime, no questions asked. It's his thanks for her saving his life.
Back at 51, Casey notices Brett and Cruz whispering and misinterprets it as another firehouse romance. To end Casey's curiosity, Brett reveals the true nature of her and Cruz's relationship: Cruz's moonlighting career as a highly rated Zumba instructor. The secret spreads through the firehouse in record time and results in the entire squad ambushing Cruz at the next class. After his shock wears off, he embraces the attention and leads them all in an intense workout.