Picking up where the winter finale left off, Dawson and Casey have to deal with Louie's biological father Andre. He goes so far as to storm into the firehouse and confront Dawson after finding out that she's retained a lawyer to fight for custody. But Brett, who reveals that she was adopted, urges the duo to work with Andre rather than against him. The duo agree to let Andre meet Louie for the first time, yet he surprises them when he fails to show up for the scheduled get-together.
Meanwhile, Severide officially consents to being Anna's bone marrow donor. But first he injures his shoulder in a rescue and then Clarke informs him that Anna's chemotherapy wrecked her immune system. That means Chicago Med can't perform the procedure. Severide is crushed by the news, gets drunk and then his Mustang is found at the scene of a vicious accident - with him missing.
And the rest of Firehouse 51 turns competitive when they discover a ping-pong table and bring it back home. Herrmann reveals that he was a ping-pong champion in 1983 and proceeds to try and school the other firefighters. Yet the competition brings out the worst in the crew, not to mention damages the firehouse, so the table goes back on the street.