As he comes around a corner in pursuit of a gunman, Davis shoots a man who is pointing a gun at Sully, unaware that the man is innocently returning the service revolver which Sully dropped when he fell. Davis's guilt leads him to doubt whether he should remain on the force, until Sully straightens him out. The tension between Bosco and Faith continues to escalate. Both Bobby and Jimmy introduce their new girlfriends to Kim, who isn't thrilled with the potential competition.

Dealing with the aftermath of gang warfare, Doc and Carlos disagree over reaching out to prevent an eleven year old boy from following his brother into a gang; Bosco's decision to turn the tables on two men who try to rob him when he's off-duty could cost him his badge when the two men turn up at the precinct to report the crime; as he continues his losing streak, Jimmy gets deeper and deeper into his bookie, which puts Joey in danger; Kim begins to worry about how much time she spends with Joey after he gets into trouble at school.

Doherty shows his bravery trying to save the mother of two young children from a fire. Meanwhile Bosco and Faith are out looking for the man suspected of starting the fire in the first place. Davis tries to set Sully up on a blind date and after her pimp beats up Malcolm's sister they try to find him before he kills the man who did it. Carlos' girlfriend problems escalate and Doc's relationship looks like going to the next stage.

Doc and Carlos are rescued by the firefighters when they get trapped in an eighteenth floor apartment with a patient who cannot walk; Ty comes to the end of his probationary period; Faith discovers that she's pregnant again; the firefighters come under fire from a madman when they arrive to fight a car fire.

Jimmy's recovery complicates his return to the firehouse as he tries to take on too much, causing discord amongst his fellow firefighters over his all-consuming need to prove his abilities have not been lost. Meanwhile, Alex Taylor joins the firehouse and arrives with some baggage of her own.

Joey starts a fire while on a field trip with his class, causing Kim and Jimmy to reevaluate their parenting styles and inspiring Kim to try to rebuild her family, starting with a reconciliation with Jimmy. But Jimmy's relationship with Brooke is not nearly as wobbly as Kim would like to think, and Kim ends up jumping into bed with a stranger and then commiserating with her mother over her problems with men, ending in a confrontation with Brooke that forces Kim to rethink what's best for Joey in the matter.

The ordeals of an elderly friend prompt Sully to consider his own loneliness; Alex regrets revealing that she discovered Jimmy on the eve of his wedding having sex with an old flame who happens to be Lombardo's current girlfriend after the news spreads like wildfire throughout the squad; Jimmy and Brooke get married.

A secret threatens to destroy Jimmy's relationships at work and home; Sully makes a date with his pretty neighbor; Bosco gets violent after his mother is beaten by her boyfriend.

The firefighters take on a rival firehouse for touch football bragging rights; Brooke files for divorce; Jimmy worries that he may be a father again.