In the middle of the day, a fire that started in a trash can near the building is raging through a machine shop. The scene is more dangerous than most - it's full of cylinders and oxygen tanks. Otis spots Ernie, the young boy from the firehouse, watching the men a few feet away. The team works quickly to keep the fire under control, but while Vargas and Severide attempt to break down the roof, a fresh batch of smoke sends Vargas to the ground in a terrible coughing fit. He's immediately taken to the hospital. When Severide spots Ernie, he turns on him, asking him if he torched the place. Chief Boden intercepts and tells Severide he's handling this, but Severide won't have it. "That's two fires, two dumpsters, same kid!" he yells furiously at the Chief.