Firehouse 51 responds to a false alarm at a private school and are delayed upon responding to an actual emergency. The male victim is badly injured and taken to Chicago Med.
Severide discovers this is third false alarm this month. He and Casey go to the headmaster for help in tracking down the culprit, but the headmaster is resistant.
Casey and Severide still try to track down the culprit and eventually find out that a little boy named Elijah is behind the false alarms after 51 responds to the school for a fourth time.
Elijah explains that he pulled the alarm because he wanted to go back to his old school. To make amends, the boy gives a card to the injured man.
Kidd is having difficulty finding Severide a birthday present, so Ritter suggests that his boyfriend Eric assist in giving her trip ideas.
Kidd settles on taking Severide on a cruise, but the surprise is ruined when Severide overhears her discussing it with the rest of 51.
Kidd then decides to celebrate Severide's birthday early, just the two of them, and Severide asks her to move in. She agrees.
Elsewhere, Brett and Cruz agree to let Nick Porter move into Otis' old room as the man is looking for a place in the midst of his divorce.
It soon becomes clear that Nick isn't a good fit, and Brett and Cruz scheme how to get him to move out. They decide to reunite Nick with his soon-to-be ex-wife Ellen, and it works.
With Nick moving out, Foster then moves in.