Tommy decides to make life a living hell for his wife's new boyfriend by wreaking havoc on his business and finances. Meanwhile, Chief Reilly faces possible suspension as the result of an altercation with a fellow firefighter and Lou decides to share his poetry.

A "friendly" date between Tommy and the widow of his dead cousin takes a unexpected turn when she makes a move on Tommy. Franco's ex-girlfriend shows up at the firehouse and claims he's the father of her five-year-old daughter, turning his life upside down.

Tommy comes to terms with the reality of his broken family as a result of a shocking experience with his father. When a freak accident occurs, Franco must make a life-changing decision, and Chief Reilly is forced to expose a family secret in order to save his career.

Tommy takes one step forward by convincing Janet to leave Roger but two steps backward when she stumbles onto his latest fling. The boys convince Sean to date a woman but neglect to tell him that she is actually a he. Franco discovers he can't shake his newfound fatherly instincts.

When Tommy asks for extra vacation time, Chief Reilly tips him off on how to get a free two week vacation from headquarters. While building a deck for Tommy's neighbor, Tommy takes advantage of his "free" advice which leads him to make a bold move in reconciling with Janet.

Tommy attempts to handle the insanity of his father while defending Colleen's new lifestyle to Janet. At the firehouse, Sean and Mike the Probie unknowingly launch a full blown wager among the crew.

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.

While Tommy attempts to make reason of the chaos in his life, he continues to defy death while pulling dangerous stunts on the job. Lou admits his infidelity to his wife and receives an unexpected surprise. When tragedy strikes his family, Tommy must come to the rescue of his father.

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.

The hockey game rematch between the NYPD and the FDNY is right around the corner and Tommy must figure out a plan to save himself from being pummeled by the cops who have it out for him. Tommy's relationship with Sheila is discovered by the guys and they must adhere to tradition to handle it in their own way. When Tommy is visited by his demons during a fire, Franco comes to his aid... with devastating results.