Dick Wolf‘s One Chicago first responder franchise has been a ratings hit since 2012’s Chicago Fire premiere, followed by 2014’s Chicago P.D., and then Chicago Med in 2015. In 2025, they’re still among NBC’s most popular shows. Here’s what’s to come when the trio of shows return together all on Wednesday nights.

Chicago Med

Several months have passed since Dr. Hannah Asher (Jessy Schram) learned she was pregnant. Is the father her former boyfriend Dr Mitch Ripley (Luke Mitchell) or lovelorn colleague Dr. Dean Archer (Steven Weber)? “Whichever it is,” says showrunner Allen MacDonald, “he’ll react with ambivalence.” Meanwhile, Ripley has moved on with Sadie (Holly Curran), whom he rescued from a well along with her young daughter (May Lansing). “He’s throwing himself completely into this relationship quicker than is probably healthy for him,” MacDonald warns.

Distressing news hit emergency department chief Caitlyn Lenox (Sarah Ramos) at season’s end, after learning she inherited her mother’s Prion Disease, which causes life-shortening motor-neuron issues. She’s now decided not to reveal her diagnosis. Says Ramos, “the story the writers are telling is what does it mean to live knowing you have a fatal disease that could strike at any time. Lenox, who’s on the autism scale, would want to help as many people as she can with the time she has, while experimenting with being alive.”

A sad farewell and a welcome return also mark the season opener. Marlyne Barrett, who has played the well-respected Charge Nurse Maggie Lockwood since the pilot, has taken a leave of absence “for personal reasons,” says MacDonald. “Maggie has planted such deep roots on the show, and it is absolutely our intention to see her again when she signals that she’s ready.”

Fans of Nick Gehlfuss‘s Dr. Will Halstead, last sighted in Season 8 moving to Seattle, will be happy to know he’s back for multiple episodes. He returns to Chicago in the 200^th episode to take the son of Dr. Natalie Manning (Torrey DeVitto) — no word if they’re still together — to a Bears’ game and drops by Gaffney. “It’s a very special episode and by the end it will feel like a big deal,” MacDonald promises.

Chicago Fire

Hard times are coming for Firehouse 51 this season as art mirrors the real-life downsizing of the Windy City’s fire department. “There will be a big effect on all our players, especially the medics,” previews showrunner Andrea Newman.

As various firehouses close, Paramedic-in-Charge Violet (Hanako Greensmith) will have her hands full managing all the ambo calls, along with fellow paramedic Lizzie (Jocelyn Hudon). Among those “riding the ambulance,” to help out the beleaguered pair: the Rescue Squad’s always amusing Capp (Randy Flagler).

In the midst of the stress, Violet, whose on-and-off boyfriend Sam Carver (Jake Lockett) left her, will now lose her House 51 bestie Darren Ritter (Daniel Kyri, exiting due to NBC’s cost-trimming). Ritter will return at the top of the season for several episodes before an emotional send-off for the popular character.

George Burns Jr / NBC

The chaos of the reductions forces Chief Dom Pascal (Dermot Mulroney) to bring in new guy Sal Vasquez (Brandon Larracuente, 13 Reasons Why), who impresses both Lt. Severide (Taylor Kinney) and the flirtatious Novak. With a lot on his plate, Pascal mostly hands over the reins to Severide, who becomes 51’s de facto leader along with an arson investigator. Domestic stress is also on its way as Severide and his unexpectedly pregnant wife Lt. Stella Kidd (Miranda Rae Mayo) prepare to be “responsible parents,” says Newman, “while they love the job in which everything you do is ‘life on the line.’”

Finally, the power switches between longtime buddies Christopher Herrmann (David Eigenberg) and Mouch (Christian Stolte) lead to a falling out after Herrmann relinquishes his lieutenant title so Mouch, who aced the lieutenant’s exam, could get the position. “Mouch really steps up and takes over,” says Newman, but things prove a bit difficult when he becomes Herrmann’s boss.

Chicago P.D.

Last season’s dark storyline culminated with Sgt. Hank Voight (Jason Beghe) arranging the murder of corrupt deputy chief Reid (Shawn Hatosy), after Reid had disbanded Voight’s Intelligence Unit and put them under investigation.

When the 13th season premieres, the team is scattered and Voight, who’s bounced down to the Rapid Response squad, is dealing with the consequences and struggling with how to fix [the situation], and navigate this by the book,” says showrunner Gwen Sigan.

Lori Allen / NBC

“His people are depending on him,” says Beghe. “He’s the liaison with the higher-ups.” Unfortunately, ASA (Assistant State Attorney) Nina Chapman (Sara Bues) has abandoned him after a bruising argument when she said she wanted more from him than a friendship. “His unit,” says Beghe, “is all that he has now.”

His crew is not doing well. Kim Burgess (Marina Squerciati) mourns the loss of her detective shield and her job “that she worked so hard for,” says Sigan. Former officer Dante Torres (Benjamin Levy Aguilar) who also lost his badge, is in crisis “and searching for something to anchor him, while Officer Kevin Atwater [LaRoyce Hawkins] does some soul searching in a thrill ride of an episode,” Sigan reveals.

Meanwhile, Voight gets a new partner: Ava Imani (Arienne Mandi, The Night Agent), who has worked with private military contractors around the world. The CPD has detailed her to the ATF as an accomplished undercover agent. “Imani is tough, rebellious and not necessarily a team player,” says the actress.

Beghe describes Imani “almost like a young female version of Voight.” Mandi’s view: “Though we don’t see eye-to-eye, we have a common goal: catching the bad guy, even if we have to cross the line.”

For Voight, as violent crimes start increasing, rebuilding the Intelligence unit “gives him a purpose,” Beghe says. “He sincerely believes that his team will make the city a safer place.”

One Chicago, Premieres, Wednesday, October 1, 8/7c, NBC