Whodunit?

When a perverted arsonist strikes Tacoma, the TPD and the TFD must put aside their rivalries to solve the case. To everyone's surprise, the two crews discover they are not as different as they think, but how long can the lovefest last?

Councilwoman Price tells Terry to find the author of an anonymous firefighter blog from the station and shut it down. With everyone a suspect, no one can be trusted. How quickly will they turn on each other? Who will crack? And Whodunnit?

Longing for a female friend, Lucy convinces Chief to transfer firefighter Delilah Dunn to the station while guys on the crew try to find a macho match to their energy. Meanwhile, Eddie takes Councilwoman Price for a walk on the wild side.

When Fire Commissioner Eddie Penisi, Sr. shows up, Eddie and Terry seek his approval while the "commish" drives them apart. The crew plays D&D for the acceptance of their own illustrious dungeon master.

Station 24 is picked to make public service announcements, forcing them to work with the buff and handsome C-Team and their new transfer Delilah. Terry buys a gas-guzzling truck and Eddie can't help but take him for a ride.

Wolf Boykins returns to lead the fire station choir, the Ex-SING-guishers. Eddie teases Granny for joining the group but soon finds himself vying for a spot as the lead whistler. Lucy, meanwhile, convinces Chief to let her look for a more female-friendly uniform.

When Lucy gets injured on the job, Eddie is tasked with heading a peer counseling session that leads the crew to learn more about themselves.

Ike's mean twin brother Mike pays him a visit and asks for a life-changing favor. Meanwhile, the crew takes DNA tests, Granny discovers his Jewish heritage and Terry is devastated to learn that Lucy's genes are more Penisi than McConky.

Terry learns some sexy new dance moves to impress Vicky at the fireman's ball. Ike volunteers to be Andy's wingman, and Lucy discovers her date is more like his mother than she realized.

As the Firefighter's Ball rages on, things go off the rails. Terry and Eddie battle it out, Ike deals with Andy after too many drinks, Lucy struggles to get alone time with her date, and Granny finds a way to ease the tension with his date.

It's a spooky evening for the crew when they have to answer a call at a haunted house. While they navigate the haunted halls looking for the source of the fire, each of them must confront their greatest fears.

The holiday season has arrived at the firehouse and everyone is feeling jolly... except for Eddie. In order to get good year-end reviews, Lucy, Andy, Ike, and Granny try their hardest to get him in the Christmas spirit.