The One Chicago franchise has captivated viewers with its narratives that are interconnected with multiple spin-offs. Created by Dick Wolf, the franchise first premiered in 2012 with Chicago Fire, which introduced audiences to the lives of firefighters and paramedics at Firehouse 51. Over the years, the One Chicago expanded to include Chicago P.D. in 2014 and Chicago Med in 2015.
The latest One Chicago crossover event premiered on January 29, 2025, consisting of three episodes. The first one was titled In The Trenches Part I from Chicago Fire season 13 episode 11. It was followed by Chicago Med season 10 episode 11, titled In The Trenches Part II. The crossover continued with Chicago P.D. season 12 episode 11, In The Trenches Part III.
What happened in One Chicago crossover episodes?

Chicago Fire season 13, episode 11: In the Trenches: Part I
The One Chicago crossover starts a gas explosion at a government building on Chicago's South Side. It causes structural collapses in surrounding areas, demanding a response from firefighters, paramedics, and police.
Stella Kidd leads the Truck to assess the situation, and they begin rescuing passengers. However, an aftershock causes a tunnel collapse, trapping Kidd and Detective Adam Ruzek inside with multiple injured civilians and limited means of communication.
The narrative then shifts to Mouch and Trudy Platt, highlighting their personal stakes in the crisis. Platt, along with Ruzek and former officer Lauren Bates, encounters the offenders responsible for the explosion.
In a shocking turn, Platt is shot multiple times by Bates, a former colleague. Mouch, driven by desperation and love, risks his life to find Platt and rushes her to the hospital in critical condition.

Chicago Med season 10, episode 11: In the Trenches: Part II
The One Chicago crossover second part shifts to Chicago Med, where Trudy Platt’s condition takes center stage. Dr. Ripley employs a cooling technique to save her life after she flatlines during surgery. The untested procedure sparks tension as Mouch struggles with the uncertainty of the treatment.
Dr. Charles steps in to provide emotional support, helping Mouch confront his feelings of guilt for wanting to return to the rescue site while his wife fights for her life.
Meanwhile, Dr. Archer surprises everyone by remaining at the hospital but offering guidance remotely. Severide, Herrmann, and Pascal continue efforts to reach the trapped victims, while Kidd tends to the injured using Archer’s medical advice over the phone.
Morever, Burgess and Voight work to uncover the motives behind the explosion. Through interrogations and leads, they discover that the explosion was orchestrated to steal a server drive containing $250 million in city employee pension funds. The stakes grow higher as the investigation progresses.

Chicago P.D. season 12, episode 11: In the Trenches: Part III
The final part of the crossover centers on Chicago P.D. Ruzek uncovers one of the offenders, Ray, among the train passengers. Though Ray claims innocence, his actions raise suspicions, leading to a standoff.
Another offender emerges, taking Kidd hostage and forcing Ruzek to surrender his weapon. The situation becomes perilous as oxygen levels drop and structural instability worsens.
The standoff in the tunnels escalates as the offenders take Kidd hostage, demanding an escape route. Meanwhile, at the hospital, Platt’s condition remains uncertain, and the investigation into the explosion intensifies.
Ruzek attempts to negotiate with the offenders, buying time as Severide and Herrmann strategize outside the tunnel. However, before a full rescue is executed, another cave-in occurs, leaving Kidd and Ruzek’s fate uncertain. Mouch remains torn between staying by Platt’s side and returning to the scene, while Dr. Archer coordinates additional efforts from the hospital.
Meanwhile, Burgess and Voight unravel the offenders’ backstory. Bates, revealed as the mastermind, confesses to orchestrating the explosion. Diagnosed with mesothelioma from unsafe working conditions, she felt abandoned by the city and sought revenge by stealing the pension funds. However, her betrayal and decision to shoot Platt underscore the tragic consequences of her actions.
Reflecting on the aftermath
Mouch’s anguish over Platt’s condition is one of the crossover's poignant moments, highlighting the sacrifices first responders make. Kidd and Ruzek’s teamwork under extreme circumstances showcases their resilience, while Severide and Burgess provide emotional anchors as they support their partners.
The crossover also explores themes of justice and betrayal, with Bates’ story reflecting the systemic failures that pushed her to desperation. Fans are left eagerly anticipating the next chapter in the One Chicago universe to find out how these heroes continue to safeguard the city.
Catch the latest episodes of One Chicago universe streaming on Peacock.