When Tommy discovers a secret that Janet is keeping from him, he must come to terms with the possible consequences. At the firehouse, Chief Reilly preps the boys for their new female replacement. With the help of Franco and Sean, Tommy tracks down the man responsible for Billy's death.

When Tommy struggles to help Janet in a financial crunch, he must turn to his Uncle Teddy to help him out. The new female addition to the house fights to be accepted by the guys while they do everything they can to drive her nuts. Just as Mike is getting fed up from sleeping on the firehouse couch, he is offered a helping hand with a free place to stay... at a steep price.

When Janet needs more money to cover house repairs, Tommy turns to Uncle Teddy and his "little" friend to help him out with extra cash. When Franco's father has a stroke, Franco finds himself trying to juggle work and raising his daughter on his own. Meanwhile, a goodwill tribute to the firefighters lost in 9/11 goes awry and the firehouse is put in jeopardy.

In the opener to the second season, troubled Tommy Gavin is having a difficult time adjusting to life at his new uneventful firehouse after the volatile split with his old crew. On top of this he is still looking for his missing wife who has kidnapped his three children and he has to come to terms with the fact that his dead cousin’s wife is pregnant with his baby. His frustrations come to a head and he has a meltdown with a street vendor selling 9/11 memorabilia.

In an effort to get more time off to search for his wife and kids, Tommy joins the new firehouse’s Barbershop Quartet. Meanwhile back at the old station, Lou and Chief Reilly conspire to get Tommy back, but the rest of the crew has grown fond of his replacement.

Tommy's fate in the firehouse depends on vote by the crew. Tommy reunites with his dad. Franco and Laura's relationship grows.

Tommy asks his cousin for help in understanding the bizarre visions he's been having. The crew tries to help Laura understand the essence of male comaraderie.

Tommy has a chance at finding his kids with help from his oldest daughter. Chief Jerry asks his son for help when his wife's condition worsens.

Tommy seeks the truth about Sheila while trying to get his kids back; Lou does not like the person he has saved through a bone marrow donation; Franco's addiction puts those he loves at risk; Sean's new girlfriend habitually dates firemen.

Franco's addiction to painkillers has driven him to a support group to get help with his problem. A young boy clings to life after Tommy saves him from a fire. Jerry is introduced to his gay son's life partner.

Jerry forces the crew to attend a birthday party that his son is throwing for his boyfriend. Meanwhile, Tommy makes a move on Mariel after she tells him she might not be his half sister after all. Franco asks Laura to move in with him while Sheila tries to make Tommy jealous by showing off her new girlfriend.

Tommy starts taking Janet's antidepressants. When Sean meddles in Franco and Laura's troubled relationship he makes things worse. After a gay visitor, the crew wonders about Mike's sexuality.

When Tommy, Johnny, and Mickey confront Father Murphy it results in tragedy. Sheila needs Tommy's help with a domestic issue. Jerry decides it's time to get a nurse to care for Jeanie. Lou offers to help Candy out with her situation. And Laura discovers the truth behind Franco's poetry.

Tommy lays off the antidepressants when he is kicked off the hockey team. Sheila asks Tommy to talk Damien out of being a firefighter. Meanwhile, when Franco sees Laura with another guy he gets jealous and Tommy's dad gets a surprise when he returns home from a three day trip to Atlantic City.

Tommy's sister suddenly shows up in town when their dad is about to inherit a million dollars. Tommy and Janet decide to renew their wedding vows. Meanwhile, Mike is worried when he finds a lump.

Tommy copes with a tragedy. Jerry must decide what to do when his wife's condition worsens. Sean has a crisis of faith. Lou learns some shocking facts about Candy. And the crew responds to a multi-level building fire with people trapped inside.