As the blackout continues throughout the city, the squads face looting, fires, and riots which occur in its wake. Battling an angry mob, Sully and Ty rescue an injured man and woman who turn out to be George Hancock, the Chief of Patrol, and his mistress Nancy. The paper publishes a picture of Ty carrying Hancock from the scene on the front page and hails Ty as a hero cop, much to his disgust. Against Ty's better judgment, Sully cooperates with the brass in whitewashing Hancock's presence at the scene. After Nancy collapses at the hospital, she is rushed into surgery, but not before denying Dr. Field's assessment that she has been raped. Bosco roams the city looking for Faith and finally tracks her down just as Faith manages to carry Fred out of the building after rescuing him from the elevator. After they race him to Mercy, an overwrought Faith lashes out viciously and unfairly, first at Proctor and then at Bosco. As painful as her words are to hear, Bosco realizes the truth behind some of them and decides to change his ways, starting with picking up Faith and Fred's kids and bringing them to the hospital and later by "losing" the evidence against Latrell and letting him go free so he can stay on the list for paramedic hires. Sully tells Tatiana that he believes her when she says that she is not the Natasha Guerin on the rap sheet with the four prostitution arrests and that it is a mistake. Later that evening after she falls asleep, Sully takes her vodka glass, puts it in an evidence bag, and hides it. Doc and Carlos argue again, and this time Doc is on the receiving end of a partner's harsh truths.

An excited Bosco signs up for temporary duty on an elite undercover unit to investigate a gang weapons ring but chafes under the authority of an abrasive female leader (guest star Elizabeth Rodriguez) while Yokas gets more bad news about Fred's heart problems. Elsewhere, a distrusting Sully learns more than he wants about Tatiana's sordid past with the Russian mob; Doc is surprised by the news that his ex, Doctor Morales, has got married, and Davis is ordered to report to George Hancock, the Chief of Patrol whose life he saved.

The frightened parents of a missing boy seek vengeance against a known child molester in their building while the police desperately search until they think they have found the victim ? but only firefighter Alex can ultimately save him. Meanwhile, an uneasy Sully reluctantly agrees to help a hated fellow cop in an undercover operation that will exploit his Ukrainian wife's secret connection to a Russian mob boss. A cavalier Carlos offers to hook up an uninterested Doc with an "older" woman.

Doherty, riding on his motorcycle, is first to arrive at a multivehicle collision. Alex is hit by a car. Tatiana goes to see Chevchenko.

Chevchenko has Tatiana's son killed. Fred comes home from the hospital. Davis gets a job offer. Tatiana confronts Chevchenko after arguing with Sully.

Sully tries to get revenge on Chevchenko for Tatiana's murder. Fred helps mend Faith and Emily's souring relationship.

Boscorelli is in the supermarket with his mother when a fire starts in the facility. When everyone is out and the ambulances are there, Bosco is told by Jimmy that he thinks the fire was started by someone. Seconds later, Bosco sees someone smiling while watching the fire and he thinks that he is the one who started it.

On their way to go shopping, Faith and Emily stop at a bank to get some money; Faith does not like automated teller machines. While they are inside, two men enter with plans to rob it. The situation gets out of control, and Faith and Emily are taken hostage along with everyone else. Faith manages to sneak a call to 9-1-1, alerting her coworkers to the situation. Posing as a medic, Bosco manages to get into the bank. The episode ends with a narration from Emily, in which she says she now has some idea of what her mother goes through each day.

Doc and Joy hook up. Miguel White (the boy from "To Protect...") witnesses one drug dealer murder another, and becomes the dealer's next target. Sully rides with Faith on his first day back at work, and she is put off by his short fuse and bad attitude. When he leaves a prisoner unguarded and uncuffed, Faith tells him to go home because he is not ready to be back on the job. Sully gets drunk and goes to his mother's nursing home. Sobbing about Tatiana, he tries to batter down the door when the receptionist refuses to let him in and she calls the police. After Hancock arrives on the scene, Sully mouths off to him about Nancy in front of the other officers who are there to take him home.

Bosco is dismayed as he watches Cruz go to the extreme lengths of planting drugs, frightening children, and faking a dying declaration in their attempt to arrest the drug dealer who killed another dealer and tried to kill Miguel; Nancy tells Ty that she's ending her relationship with Hancock, and gives Ty the ammunition he needs to get out from under Hancock's thumb and back to duty at the 55, as well as getting Sully's suspension from duty lifted.

Doc supervises a new paramedic on her first day; Carlos is arrested after a teenaged patient accuses him of molesting her; Bosco and Faith search for an escaped prisoner; Sully and Davis team up with fire and EMS to save construction workers when their scaffold collapses; in the aftermath of the bank robbery, Faith is troubled when Emily asks her how many people she's killed in the line of duty.

Ty bails Carlos out and unsuccessfully tries to help him smooth things over with Nicole; after Bosco and Faith break up a domestic disturbance between an old friend of Faith's and her lover, Faith convinces her friend to leave the abusive relationship; Alex gets irritated when the other firefighters make fun of her brother; Sully continues to drink and have a poor attitude on the job; Jimmy is appalled when his face appears on a poster for an erectile dysfunction product and that the company paid the charity for whom he posed for the picture $10,000 for the right to use it, until he discovers their website got 3,000 hits the first day from women wanting to know his name; when he discovers that everyone thinks that he's guilty and he's likely to lose his case, Carlos resigns in the hope that Nicole will drop the matter, and he'll be able to avoid a conviction that will end his visits with Kylie and his hopes of becoming a doctor.

Sully's stopped drinking, but his poor attitude remains; Carlos gives his two-week notice; a blizzard blankets the city and the squads are called in early; an understaffed Doc defies orders and puts Carlos back on the street as the squads are kept busy rescuing victims of the storm; Faith's initial wariness about Emily's new boyfriend Eric turns out to be well-founded when he is brought into Mercy after an overdose of Special K, but doesn't remember where he left Emily after she also got high; Faith, Bosco, Sully, Ty, Doc and Carlos go out to search for Emily, and rush her to Mercy after she's found in critical condition; Faith and Fred blame each other for letting Emily go out with Eric.

As Faith waits for Emily to awaken from her coma, she blames everyone but her daughter for the overdose and reflects on the substance abuse problems in her family; after Cruz's sister is brought into the hospital with an overdose, Cruz gets Sully, Ty and Bosco to look the other way on any possession charges and sets off with Bosco to find the location of her supplier's meth lab, where they end up in an inferno when the dealer sets the house on fire; Kim is reluctant to give a statement in Carlos's case because she's feeling pressured to lie to save his career.

As she keeps vigil by Emily's bedside, Faith recalls her first days at the Police Academy and the beginning of her friendship with Bosco; the fire squad rescues Bosco, Stg Cruz, and a very pregnant Linda Barnes from the inferno, but Lettie Cruz dies before they can reach her; Emily is released from the hospital and takes responsibility for her overdose; Bosco tracks down Gary Barnes with Linda's help; Cruz and Bosco's relationship goes to a new level when he attempts to comfort her on the loss of her sister; Kim finally testifies before the review board and stands up for Carlos.

Sully hits bottom when Ty washes his hands of the partnership after the former's drinking goes completely out of control; a thief strikes fear in the hearts of the police when he phones in false "officer-in-need-of-assistance" calls to cover his fur store robberies; Faith and Cruz go at it after Cruz's lonesome cowboy tactics nearly gets another cop killed, and Faith is forced to shoot a perp to save Cruz's life after she goes after the perp without backup; Doc has an unpleasant encounter with Joy's father; Faith is disgusted when she finds out about Bosco and Cruz, and Cruzconfirms that she put Bosco in front of a lie about a dying declaration to obtain a conviction on a drug dealer; Ty overcompensates for Sully's lack of attention to the job by becoming a "supercop" with an eye on getting a gold shield.

Faith rebuffs Bosco's attempt to apologize for lying to her. The fire squad extricates a driver impaled after crashing into a store. After Doc makes an impassioned defense of Carlos before the review board, a re-energized Carlos goes back out on the street. Sully's performance on the job continues to decline as he neglects to keep an eye on a woman he was supposed to be guarding and she snatches her critically ill baby from Mercy's E.R. After they discover that the woman is mentally ill, Ty takes a multi-story tumble while trying to prevent her from jumping off a roof with the baby. Faith is stunned when an initially reluctant Emily is eager to continue visiting a drug counselor. Ty catches Sully drinking in the patrol car and seeks advice from a union rep. Carlos loses his job as part of the department's settlement with the West family.

In a last-ditch effort to save Sully's life, job, and pension by getting him dried out, Ty and Bosco kidnap him and bring him to a cabin deep in the woods where he hallucinates about the circumstances surrounding the deaths of Tatiana, Chevchenko and Ty's father, and his subsequent descent into alcoholism.

Sully is sober and back on the job. Faith continues to keep a close watch on Emily. A mutual attraction springs up between Kim and a reporter. Faith and Bosco pursue a man after he steals a bag of money from an overturned armored car involved in a fatal accident. Faith is unable to dissuade Bosco from wanting to hide the cash after the robber drops it, rather than carrying such a heavy load during a foot chase, and is proved right when they return later to retrieve the bag and find that it's been stolen yet again. Faced with disciplinary action and investigations by the Major Case Squad and IAB, they pound the pavement trying to find the second perp and discover that the accident with the armored car had been staged by one of the guards and his girlfriend. As Doc and Kim rush Nicole West to Mercy after a suicide attempt, she tells Kim that her stepfather Anthony has been molesting her. When Nicole's mother refuses to believe that her husband has done anything wrong, Kim implores Melinda to see that her daughter is crying out for help with repeated suicide attempts. After Nicole convinces Melinda that Anthony is guilty and reveals that her accusations against Carlos were false, Melinda apologizes and withdraws her complaint against Carlos and the city. Still at odds over trust and honesty issues, Faith and Bosco trade painfully honest barbs and decide to split up. Carlos is elated when Ty tells him he's being reinstated.

Kim is invited to a party by Noble. Noble is arrested through an undercover operation. He becomes an informant and helps Cruz and Bosco bust a Meth ring. Faith officially requests a new partner. Emily and Faith face off about Eric.

Cruz's desire to find the leader of the Meth ring puts Bosco in an uncomfortable position. Faith tries to improve her relationship with Emily and also gets a new partner, Sasha, at work. Noble is released and sets up a new date with Kim.

Maritza's reckless pursuit of Buford, (the meth ring leader) triggers a horrific car accident that leads to multiple injuries as well as a massive explosion that severely injures Lt. Johnson and kills Alex Taylor. Doc and Kim get to the top of the promotion list. Maritza hangs Bosco and Nu?ez out to dry over the murder Noble committed. Doc's overwhelming guilt and grief over Alex's death leads him to a career decision. Maritza discovers that Faith has agreed to help Bosco clear Nu?ez by getting Noble's gun, and goes to Noble's place to intercept her, followed by Bosco and Noble. When Bosco insists on arresting Noble and Faith refuses to turn over the gun, Maritza draws on Faith, Bosco and Faith draw on Maritza, and three shots ring out.