Bosco, Yokas, Sully and Davis search for a cop killer on the streets, and cope with an obnoxious new sergeant at the station house.

Sully is upset when he is wrongly accused of falsifying evidence; Bobby helps one of his former teachers dying from cancer; Carlos deludes himself into thinking that Kim is falling in love with him; Sully gets closer to his pretty neighbor.

Faith, Bosco, Carlos and a wounded Doc find themselves trapped in an abandoned tunnel and unable to reach Central on their radios; the firefighters get into mischief during a long lull between calls; when the C.O. can't raise Bosco on the radio, Sully tries to cover for him.

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.

Jimmy and Kim, still locked in a custody battle over Joey, meet with a court-appointed evaluator and plead their cases in a heated exchange.

When Sully and Tatiana visit his mother at her nursing home, Tatiana expresses concern over the quality and cost of his mother's care. Convinced that she can do a better job of taking care of her at home, she signs her out and moves her in with them. Sully is shocked and displeased, and tells Tatiana that it will be too difficult for her to take care of his mother.

Alex tries to stay busy to avoid dealing with her feelings about her father's death. Eager to fill empty hours and maintain the brave front her father insisted upon when she was growing up, she works extra shifts and even helps Carlos and Ty move into their new apartment. While Carlos is downstairs unloading the truck, Alex takes Ty up on his previous offer to talk and asks him about his father, who also died in the line of duty.

Feeling betrayed, Doc angrily confronts Jerry Mankowitz for tricking him into confiding vital information about a pending malpractice suit by not revealing that his old partner is now working as an attorney's investigator. Later, when Doc heroically responds to an emergency involving a near-comatose elderly woman trapped in ice, he remembers that his job is worth the legal fight ahead. Meanwhile, Carlos worries that he got the wrong telephone number from his latest romantic conquest. Faith thinks that troubled Bosco has lost his enthusiasm for police work. Jimmy struggles to act as both mother and father to Joey.

When a blackout strikes the city during a heat wave, Sully prophetically warns the more optimistic Ty that trouble in the streets will swiftly ensue. After Carlos leaves the ambulance running to keep the bus cool while he and Doc are on calls, the engine catches fire and the ambulance is destroyed. A wealthy old man confined to his bed by illness offers them a large amount of money to stay with him until his daughter arrives. Doc insists that they leave to treat others more in need over the protests of Carlos. Bosco arrests a young man, Latrell Griffith, and faces a difficult decision when an immigrant shop owner shoots and wounds a teenage shoplifter. After Latrell uses his training as a medic to save the boy, a riot breaks out and Bosco, Latrell and the shoplifter barely escape. Nightfall brings more unrest as the nervous cops try to keep the peace. Faith and Fred are stuck in a elevator when the power goes out. Faith tries to calm Fred's mounting anxiety about being trapped, and is