It sounds like you're referring to which is the sixth episode of the first season of the NBC drama Chicago Fire .
This episode is widely considered a "good piece" of television because it serves as a major turning point for the show's early storylines. Key highlights include: [S1E6] Rear View Mirror
: Casey puts his life on the line during a massive apartment building fire, leading to a high-stakes rescue that ultimately provides the break he needs to take down Voight. It sounds like you're referring to which is