The One Chicago crossover event featured the windy city caught in the outbreak of a deadly infection killing many, but the road to finding a cure might have secured a new love interest for a fan-favorite character. The three-hour event brought Chicago Med, Chicago Fire and Chicago P.D. together for a high-stakes mission to stop the spread of a man-made flesh eating bacteria infection. The investigation into a cure brought a new doctor into the hospital, with surprising and possible romantic connection to a beloved character.
As the infection escalates into a possible epidemic at the hospital, Sharon (S. Epatha Merkerson) requests help from the CDC to find a possible cure before any more deaths go on. The organization brings in a new doctor, who immediately notices Will (Nick Gehlfuss).
They reveal the pair studied together in college during their undergraduate studies. Sharon is happy about the coincidence and assigns Will to work alongside the new doctor to find a cure.
Will and Danover (check spelling) are busy with their life-threatening mission throughout the episode, but take some times to catch up while doing work in the lab. After they discover that the spears of the bacteria is an act of terrorism, Will and the Danover come together in the lab to start researching possible antibiotic treatments.
During their conversation, she admits she had a crush on him in college. Will can't believe he didn't realize it at the time, and she criticizes men for being so obtuse. They discuss their relationships and Will recalls getting close to marrying Natalie (Torrey DeVitto). Danover says she is in the middle of a divorce.
Their flirty conversation is interrupted when they realize the infection is a lot more aggressive ad dangerous than they thought, and they have to ask the biologists who worked at the local university for help.
Later in the crossover, the biologists start to work with Will and Danover and they seem to be making progress. Things take a turn when the Intelligence unit realizes one of the scientists is actually the one who planned the outbreak of the deadly bacteria.
The episode then shows the man asking his partner to get away from the cultures they worked on with Will, and he attempts to sabotage the research. Will finds him when he's destroying the cultures. He claims they were contaminated and then tackles Will. He injures Will and runs away. Jay (Jesse Lee Soffer) finds Will and makes sure he's O.K. before heading to find the man, and Danover flirts with him once more.
Despite the setback, Will and Danover manage to save some of the samples and find a treatment to the dangerous infection. The Intelligence unit then solves the case for a happy ending.