Infection

"Infection" is a three-part fictional crossover event that exists within the Chicago television franchise. The event aired on NBC consecutively in three back-to-back one-hour time slots on October 16, 2019. It began with "Infection: Part I" of Chicago Fire, continued with "Infection: Part II" of Chicago Med, and then concluded with "Infection: Part III" of Chicago P.D. All three episodes followed a unified story line of an infection spreading across Chicago and the first responders dealing with the repercussions. Many actors in the franchise appeared outside of their main series and in all three parts of the crossover. Plot Part 1 At a Chicago Bears game, members of Firehouse 51, the Intelligence Unit, and Chicago Med are tailgating. After Matthew Casey notices a guy collapse in the middle of the festivities, they head over to help and find the guy with a flesh-eating infection on his legs repeating the letters "BRT." The guy is taken to Chicago Med where they identify the infection as necrotizing fasciitis. Ambulance 61 gets dispatched to a house where they find two people dead inside from the same infection. Jay Halstead identifies the original victim as a student at a local university. Cruz reveals to Mouch and Brett that he plans on proposing to Chloe. Burgess responds to a call at a gas station where a woman and her child are both infected. They both shortly die later at Chicago Med. Boden begins dealing with the mayor's office when the house is assigned to parade duties. Firehouse 51 responds to a fire at Central Chicago University (CCU), where a large chemical fire has broken out. While in the basement rescuing trapped people Severide notices a panel on the wall with the same "BRT" initials. The discovery allows intelligence to begin putting together a connection between the infection and the university. After shift Chloe breaks up with Cruz. Intelligence discovers that the original victim was a lab assistant at CCU and had previously been threatening professors with an apocalyptic-type event happening in Chicago. Burgess and Upton go to Chicago Med to question him; however, when they arrive, they are told he died. The Office of Fire Investigation determines that the fire at CCU was deliberately set. Jay Halstead finds out that another lab assistant at CCU, Veronica Song, was supposed to be in the lab at the time of the fire but didn't show up. Upton arrives at Song's house to question her; however, upon entering Song collapses from infection.