When Brett and Mackey's lives are in danger, Casey rushes to help them.
Both paramedics are OK, and they save the live of the driver who ran them off the road.
Brett later comments about how Casey was there for her and says it's always been him.
She tries to backtrack and tells Kidd she wants to pretend like it never happened, saying things are complicated between them.
Casey later confronts Brett about her avoiding him, and they kiss.
Brett then asks what would happen if Dawson came back and asked Casey to go away with her.
Casey doesn't have an answer, and Brett asks him to leave.
After the accident, Mackey questions whether she belongs at 51.
Cruz offers her support, and she eventually decides to stay.
Ritter and Gallo offer to help Boden with paperwork.
During a call, Ritter races onto the train platform and saves a woman who collapsed.
Mouch later gives Ritter his uncle's pen back to him.
Kidd restarts Girls on Fire and tries to get her first recruit Kylie back.
Kidd discovers Kylie is working a minimum job to help her family out and between work and school doesn't have time for Girls on Fire.
Kidd then gets Kylie a job at 51 doing clerical work, which will also allow her to participate in Girls on Fire.
Severide goes to great lengths to get the old door for Ambo 61, which bears Shay's name, and reattaches it to the new rig.