As Eddie prepares to become a father, the rest of the crew's wagering gets out of control, forcing Terry to ban all gambling from the firehouse; the crew finds creative ways to bet behind Chief's back, causing Lucy to fall into debt.
When a perverted arsonist strikes Tacoma, the TPD and the TFD must put aside their long-standing rivalries to solve the case; to everyone's surprise, the two crews discover they are not as different from each other as they think.
Councilwoman Price wants Terry to find the author of an anonymous firefighter blog from the station and shut it down.
Longing for another female friend, Lucy convinces Chief McConky to transfer firefighter Delilah Dunn to the station; threatened by their female force, the guys on the crew desperately attempt to find a macho match to their energy.
Eddie Penisi, Sr. shows up at the station unannounced, Eddie and Terry vie for his approval; the rest of the gang embraces their inner nerd playing D&D to win the acceptance of their own illustrious dungeon master.
Station 24 has been selected to create public service announcements for the city, forcing the gang to work together with the muscled and movie-star handsome C-Team and their newest transfer, Lucy's old friend Delilah.
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 looks for a more female-friendly uniform.
Eddie is tasked with heading a peer counseling session that leads the crew to learn more about themselves; Terry is forced to confront the dangers of his daughter working as a firefighter; Andy comes to terms with a shocking family secret.
Ike's mean twin brother Mike pays him a visit and asks for a life-changing favor; the crew take DNA tests; Granny discovers his Jewish heritage; 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; Lucy discovers her date is more like his mother than she realized.
Terry and Eddie battle it out while stuck in an elevator; Lucy struggles to get alone time with her date; Granny finds a way to ease the tension with his date.
It's a spooky evening for the crew when it must answer a call at a haunted house; while navigating the haunted halls looking for the source of the fire, the crew members must face their greatest fears.