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.

Bobby's attempt to keep Paulie away from drugs ends tragically.

Bosco runs from the present and his past when he is wrongly suspected of murdering a sexual-assault suspect. As Faith tries to gather evidence to clear him, Bosco turns to his dysfunctional family, including his alcoholic mother, drug-addicted brother and estranged, abusive father. An emotionally rattled Kim virtually kidnaps Joey from Jimmy while Carlos actively solicits Ty to be his new roommate.

Faith returns to work from a few days off. She apologizes to Bosco for hiding her illness and promises to never shut him out again.

Filled with guilt, Doc begins to second-guess himself on every call. Kim reminds him that Ryan would have choked to death had Doc not removed Ryan's collar and intubated him. She also tells him repeatedly that everyone makes mistakes, but her words don't seem to have any effect. He begins to visit Ryan daily, clinging to the slim hope that the paralysis may only be temporary, resulting from bruising to the spinal cord. Doc's prayers are answered one evening when Ryan is able to move his fingers.

Kim and Doc treat a junkie whose boyfriend maintains that she was injured in a fall. When it becomes apparent to them that her injuries were caused by a beating, the boyfriend flees the scene. Soon after they arrive at the hospital, she dies, and the hunt is on for her killer.

The police officers sort through the carnage and count their dead in the wake of a shootout between rival gangs. While Faith tries to interrogate Fyodor Chevchenko, a ruthless Russian mobster, Sully worries about the severely wounded Ty and regrets causing the incident. Tatiana chastises Sully for hassling her injured son. Faith worries about Gusler, her ineffective, frightened rookie partner, and a weary Doc gets some unexpected good news about his medical malpractice suit.

During the investigation of the gang shootout, the officers are questioned and presented with evidence which suggests that Ross was killed by friendly fire; Carlos learns that Vangie is dead and that he might be the father of the baby her sister leaves at the firehouse; on the first anniversary of Bobby's death, Kim quarrels with Jimmy over her visitation with Joey and confronts a female gang during a call; and Doc is visited by the father of a former patient whose debilitating injury may have been caused by Doc's error during treatment.

Hopelessly in love with Kylie and concerned that she will lose her Latina heritage if she is adopted by a white couple, Carlos considers raising her until he realizes that the couple can give her the sister, the grandparents, and the extended family that he cannot; Kim's preoccupation with her new PDA drives Alex crazy until they are able to use it to save a very sick man, thus redeeming themselves in the eyes of a hypercritical Dr. Peterson; Faith and Fred are still on uneven ground about the sergeant's exam; in an effort to shake Chevchenko's tree, Faith and Sully execute a clever plan to disrupt the Russian's bookmaking operation, which also opens the door to the possibility of the still-missing Tatiana's return; Bosco is cleared for duty, and he and Faith agree to be partners again as soon as he returns.