S5, E5: Lt. Casey (Jesse Spencer) is unable to rescue a woman who becomes trapped inside her burning greystone, prompting him and Lt. Severide (Taylor Kinney) to butt heads over the husband's role in the tragedy. Herrmann (David Eigenberg) is on a mission to catch a mystery tagger that keeps targeting their firehouse and Boden gets a surprise visitor. Meanwhile, Dawson (Monica Raymund) and Brett (Kara Killmer) respond to a 16 year old boy who was injured during a romantic homecoming proposal.