Many One Chicago stars have crossed over between shows, but perhaps the most frequent character to do this is Desk Sergeant Trudy Platt (Amy Morton). For both professional and personal storylines, we’ve seen Platt many times across Chicago P.D. and Chicago Fire — and a few episodes of Chicago Med.

Platt’s mostly a mainstay on P.D., where she’s the Intelligence Unit’s ride-or-die. But in a teaser for the Chicagos’ first three-part crossover in five years, we learn she’s in the hospital — squarely in an episode of Chicago Med. What’s wrong with Platt? Is she going to be OK? Only time will tell, but you can bet her Firehouse 51 husband, Mouch (Christian Stolte), is stressed.

As we wait to find out what happens to Platt during One Chicago’s crossover event — kicking off January 29 at 8/7c with an episode of Fire — let’s learn a little more about her history with the franchise.

Trudy Platt has been on Chicago P.D.​​​​ ​​​since the 2014 pilot (“Stepping Stone”). She’s the mother of the Intelligence Unit and fiercely protective of her squad…while also never letting them slack off.

Platt may seem tough as nails on the outside, but she’s secretly fuzzy on the inside. That paradox — not to mention her romance with Mouch — has made her one of the Chicagos’ most beloved stars.

How long has Trudy Platt been on Chicago Fire?

Platt has been in 39 episodes of Chicago Fire, first appearing in Season 2, Episode 16 (“A Rocket Blasting Off”).

We’ve seen many One Chicago romances blossom over the years, but Platt and Mouch’s is a standout. The unlikely pairing, known as “Plouch,” is a shining example of how opposites attract. Mouch is gregarious, relaxed, and funny; Platt is a bit more by-the-book. Yet, they work.

The pair first met at Chief Boden’s (Eamonn Walker) wedding in Chicago Fire Season 2, Episode 22 (“Real Never Waits”). It didn’t take long for them to begin dating, eventually tying the knot in Season 4, Episode 18 (“On the Warpath”).

Platt is one of the co-owners of One Chicago watering hole Molly’s, along with Mouch and his good friend Herrmann (David Eigenberg), so she’s made dozens of Chicago Fire guest appearances.

Trudy Platt has appeared in every One Chicago show

So far, Platt has also appeared in three episodes of Chicago Med (with the crossover, it’s now four), as well as an episode of Chicago Justice, which is no longer airing.

While Platt’s return to Med could undoubtedly be under more ideal circumstances, fans are ready to find out what happens to her!

One Chicago’s Crossover Event Is Here!

Hey, ChiHards! Don’t miss the intense three-hour One Chicago crossover event on Wednesday, January 29 at 8/7c on NBC and streaming on Peacock. Get ready for edge-of-your seat drama starting with Chicago Fire, then Med and onto the big conclusion with Chicago P.D.

Plus, the excitement doesn’t end there!

From Thursday January, 23– to Saturday February 22, Xfinity will be running a Rewards Sweepstakes where fans like you can enter for a chance to win One Chicago merch and autographed memorabilia for you and a friend.

Then, from Wednesday January 29 to Tuesday February 4, enjoy One Chicago Bingo. Watch the crossover episodes of Fire, Med and P.D. and play along on NBC.com desktop and mobile.