On the last "Chicago Fire," McLeod prepared for an all-out war and Shay got closer to hitting rock bottom.

In "Rhymes with Shout," Detective Voight (Jason Beghe) returns to investigate a gang shooting that Cruz (Joe Minoso) and his brother Leon (Jeff Lima) were involved in. A young girl they knew died from a gunshot wound, so they need Leon to go undercover to infiltrate the gang and crack the case. Cruz at first refuses, but Voight brings up the Flacko incident to use against him.

Gail McLeod (Michelle Forbes) is back at Firehouse 51, and is waging war against Chief Boden (Eamonn Walker) after the stunt Boden pulled on the last episode. She wants to shut down 51, so Boden begins to formulate a plan to get rid of her for good.

Shay (Lauren German) transferred to another firehouse, unbeknownst to Dawson (Monica Raymund). Dawson and Shay are still on the outs, and refuse to talk to one another. Dawson gets a new partner, Chout, who asks Dawson out on a date, but Dawson is not interested.

Meanwhile, Shay gives Devon a key to the apartment, and Shay returns home to find that Devon stole all of the valuables when she wasn't home.

It's also revealed that Clarke's (Jeff Hephner) wife is in debt, and that Clarke has a rifle in his trunk.

Cruz finally asks Zoya (Larisa Polonsky) to marry him, meaning she'll be able to stay in the U.S.

Casey (Jesse Spencer) and Dawson are slowly starting a relationship, but are still unsure about embarking on a serious romance.

On the next episode, "You Will Hurt Him," "Boden prepares a final counterattack to save the station while Dawson and Casey's romance escalates."

Watch the promo for "You Will Hurt Him," which airs Tuesday, Dec. 3 at 10 p.m.