Mia Hulen

Truck and squad are called to aid in a massive all city response when an old, ill equipped factory turned live/work space quickly turns into a firestorm, trapping countless unsuspecting victims. The dire situation quickly turns personal when it is discovered that one of Chicago PD's own has a family member at the scene. With the rescued victims in need of serious medical attention, the doctors and nurses of Chicago Med are tested as the major influx of patients are brought through their doors. Meanwhile, in the aftermath, the building owner steps forward to cooperate with the ongoing investigation, but the situation takes a sudden and unexpected turn.

When the squad's rig breaks down in the field, Casey (Jesse Spencer) reunites with his old friend and colleague Jason Kannell (guest star Kamal Angelo Bolden) from Squad 6, whose crew gets assigned a temporary change of quarters until the rig issue is resolved. Dawson (Monica Raymund) and Brett (Kara Killmer) serve their time in retraining, both tackling the class in unique ways. Severide (Taylor Kinney) tries to remedy what is going on with Anna (Charlotte Sullivan) and finds support from unlikely sources. As Connie (DuShon Monique Brown) returns from her family engagement, the crew lays bets on how long her temporary replacement Marcy (guest star Mia Hulen) will last.

When similar car accidents uncover the fact that someone may be targeting innocent people, a determined Dawson (Monica Raymund) takes matters into her own hands to help push things along. Severide (Taylor Kinney) does everything he can to make Anna (guest star Charlotte Sullivan) feel welcome in her new Chicago surroundings. Herrmann (David Eigenberg), Kidd (Miranda Rae Mayo) and Dawson decide to have Molly's included as a stop in this year's pub crawl, despite strong concerns from Otis (Yuri Sardarov), who may have his own reasons for standing alone. Meanwhile, Casey (Jesse Spencer) tends to his Alderman's duties when a persistent constituent asks for his help in resolving an issue.