It is September 21, 2001, and the squads continue to battle through their emotions and their misgivings about their hero status, while working double shifts and spending every free moment at "the pile" searching for the missing. Kim returns to work and teams up with Doc, which allows an emotionally frayed Alex to return to paramedic duty; an exhausted Sully attempts to co-exist with his prospective in-laws while he waits for an opportunity to marry Tatiana.

After a despondent woman steps off an eight-story apartment building, the squad finds themselves in a race to transport both the woman's heart and a dying girl to a local hospital in time to save the youngster's life. The suicide hits home for Faith as she comes to grips with her own ongoing medical problems, while Doc expresses concern over the emotional effects this case will have on Kim, despite her constant reassurance that her accident was not an attempt to kill herself.

Even though his co-workers want to nominate him for the "Paramedic of the Year" award, a pensive Doc is disheartened as he considers his unfulfilled life. He later teams with Kim as they try to save a heart-attack victim while fending off a woman wielding a meat cleaver. In addition, Doc tries to minister to a chronic old drunk and a teenaged girl who attempts suicide in her bathtub. Meanwhile, Faith secretly undergoes a procedure to determine if the lump in her breast is cancerous, leaving an unsuspecting Bosco assigned to a nervous rookie cop; Kim reluctantly consults a lawyer about Jimmy's intention to claim custody of Joey.

During a sweep for prostitutes, Faith and Bosco tragically misjudge a sexual encounter between a young woman and a man in a car to be consensual; the situation spirals out of control when the girl later claims she was sexually assaulted while the cops laughed it off; Carlos considers a willing Ty as a potential roommate candidate.

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.

No one can find Bosco after a sexual assault suspect is found dead. While Bosco spends time with family, Yokas, Ty and Sully try to clear him as a murder suspect. Still locked in a custody battle over Joey, Jimmy and Kim meet with a court-appointed evaluator and plead their cases. Alex tries to stay busy to avoid dealing with her feelings about her father's death.

Kim and Jimmy are having a custody battle over Joey. Boscoe and Faith are on a call of a possible terrorist threat, that ends up being an explosive event. Alex risks herself to save a little girl and is punished by Doc for it.

Doc is up for paramedic of the year and is being followed by a film crew. Doc may have made a medical mistake when treating a patient. Faith recovering from cancer treatment and on the job fails to back up Boscoe while chasing a suspect.

After seeing his young son Joey fall and break his arm in a playground accident, Jimmy fights through a burning apartment building to save a frightened boy of Joey's age. Meanwhile, a guilt-ridden Doc can't stay away from a recuperating teenager, Ryan Buckley, who was accidentally paralyzed while under Doc's care. Taylor is annoyed by a new probationary firefighter, Ken Prescott. Bosco and Yokas search for a drug addict who murdered his girlfriend.

Carlos has a life-changing experience in the hospital after he falls down the fire pole. Tatiana leaves her mother-in-law alone in the house for a moment, with disastrous results.

Bosco tries to protect an old ESU sharp shooter from spiraling out of control. Faith contemplates taking the sergeant's exam. Davis and Taylor have a steamy affair. Doc feels the guilt over a mistake that made a boy a paraplegic.

Feeling betrayed, Doc angrily confronts his former friend, Jerry Mankowitz, an attorney's investigator who tricked him into confiding vital information about a pending malpractice suit.

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 mob boss, 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 police officers are questioned and presented with evidence that suggests that Ross was killed by friendly fire; Carlos learns that Vangie is dead and that he is 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.

Bosco starts having panic attacks and goes to see a therapist, but it doesn’t work and later he turns to the only person who’ll listen. Carlos is discovering the trials of single parenthood and starts thinking about adoption. Faith is studying for the Sergeant's exam. However, her concerns about Bosco’s mental and emotional health cause her to fail, and this angers Fred, and he storms out of the house. But later, he sees Faith comforting a sobbing and weeping Bosco after Bosco admits that he couldn’t go back to the World Trade Center towers after they fell down.

Tatiana is still missing, and Sully continues to search for her while grieving her loss. When he comes upon the body of a six-year-old girl in a box on a curb, he becomes strangely unnerved. Haunted by this sight and by thoughts of the mistakes he has made recently, Sully takes the rest of the day off sick and winds up in a local restaurant where he finds his parish priest. They ruminate on the nature of guilt, absolution, forgiveness, faith, and the intercession of God as they recall the fate of another man who also made mistakes and tried to fix them, and whose life ended tragically at Sully's hand. Sully finally comes to a place where he can forgive himself and go on with life. He seeks out Davis to once again beg his forgiveness and reaffirm their connection to each other.

When a doctor comes to New York to search for the missing daughter of her drug-addicted sister, Faith and Bosco focus their attention on the child's stepfather, a New Jersey cop, after they discover that the girl was taken by a man in uniform; Tatiana returns home; Jimmy spends some quality time with Joey. The crossover starts on ER S08E19 Brothers and Sisters

Rescuers find the body of Alex's father, and he is given a hero's burial; Faith and Bosco tail a convicted rapist released on appeal, certain that he will rape again; dissatisfied by Tatiana's explanation of her whereabouts the eight weeks she was missing, Sully investigates further and uncovers some astonishing and heartbreaking facts about his wife; after Chevchenko threatens to kill him if he doesn't roll over on Faith and Sully, Frankie tells Swersky that the raid on Chevchenko's numbers business was a hummer bust, leading Chevchenko to threaten a lawsuit and have another angry confrontation with Sully.

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