The house welcomes a new candidate, Jimmy Borrelli , whose arrival is marked by a prank that goes wrong. Later, Stella Kidd joins the team, bringing a fearless attitude and a shared history with Severide. Personal Arcs & Relationships Chicago Fire Season 4 - My Entertainment World -
Season 4 focuses on major leadership shakeups at Firehouse 51, intense personal trials for its leads, and dangerous undercover operations. The overarching story is defined by the following key developments: Leadership Crises & Firehouse Dynamics Chicago Fire - Season 4
Kelly Severide is stripped of his rank due to high turnover on Squad 3 and must attend leadership training. Captain Dallas Patterson takes over his command, creating significant internal tension. The house welcomes a new candidate, Jimmy Borrelli