Mercy's new E.R. attending gives the cops and paramedics a hard time while ignoring Carlos's attempts to hit on her; Doc is saddened to hear that Jerry has decided to take a disability retirement; Jimmy is upset when Joey goes to Bobby first after he becomes ill as a result of Jimmy's letting him overindulge in sweets; Jimmy and Bobby take out their conflict over Kim and Joey in a game of one-on-one; Sully and Ty arrest a purse snatcher who will do anything to stay in jail once he discovers that his victim's son is a mobster; Faith hands out street justice to a gangbanger responsible for the deaths of two little boys.

An explosion in a building about to be demolished leaves men trapped inside, forcing the firefighters to make terrible choices; Fred's drinking problem escalates; Doc cancels his date with Brenda.

Sully lives his worst nightmare as the police search the city for a man who is buried alive and whose kidnappers are involved in a fatal car crash; Kim and Bobby find an abandoned 4 year old boy wandering the streets; Sully's mother wanders off from her nursing home; Carlos adopts a deceased patient's cockatoo.

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.

While coping with work demands, a recovering alcholic husband and a disturbing visit with her parents, Yokas confronts her long held beliefs and emotions.

A group of prisoners escape from a delivery truck. Yokas and Fred have another big fight in which she accuses him of drinking again. She tells him that she had an abortion. He wants her to leave the house, this makes her stay over at her parents home. However, by the end of the episode, they are back together, she realises that she can't live without him and that she is sorry for accusing him of still drinking.

Meanwhile, Bosco gets a bunch of flowers from a former lover. He smells the flowers which turn out to be poison Ivy. Bosco and Yokas also have a fight when she tells him that she had an abortion. He accuses her of lying to him and he refuses to speak to her, until she forces him to go the hospital to sort out the poison Ivy problem. She regrets lying to him.

A disturbing visit from his former high school girlfriend forces Doc to confront a horrible act he has hidden for years; Carlos struggles to pass a medical school qualification exam.

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.

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.

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

Doc and Carlos attend a stress debriefing; Carlos meets up with Bosco when he's ordered to attend sensitivity training.

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.

Faith and Bosco hunt down the dealer who distributed a batch of lethal heroin; depressed over Bobby's death, Kim attempts suicide.

Ty, Sully, Bosco, and Faith rush to the scene of a school shooting; Sully and Tatiana ponder their future together; Kim continues to struggle with her depression.

On September 10, 2001, Ty and Sully are in Atlantic City on the eve of Sully's wedding to Tatiana. Kim sinks deeper into depression. Bosco searches for anything to do after someone lets out the result of the Giants game he had taped to watch after shift. Jimmy keeps trying to catch up on some sleep after nursing a sick Joey.

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.

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.

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.

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.

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.

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.

Bosco gets a temporary assignment working with a tough female sergeant; Fred is strangely calm in the face of the prospect of a triple bypass; Doc hears shocking news from Philadelphia; Sully learns more about Tatiana's past; Davis is forced to deal with his newfound fame.

Yokas and Bosco try to find a missing boy whose parents think has been taken by a registered sex offender; Sully prepares to be questioned about his wife's background

Doherty, riding on his motorcycle, is first to arrive at a multivehicle collision; Taylor is hit by a car; Tatiana goes to see Chevchenko, and tragedy ensues.

When a fire breaks out in the supermarket where Bosco and his mother Rose are doing some late night shopping, Bosco rescues most of the shoppers but cannot save a young mother when she goes back inside to retrieve her purse. After Jimmy tells him that the fire was probably deliberately set, Bosco is convinced that he saw the arsonist in the crowd outside after the fire. Sgt. Cruz gets Bosco and Faith assigned to the Anti-Crime Unit for a few days so that they can track the guy down. At the scene of another supermarket fire the next night, Faith takes down license plate numbers, Cruz photographs the crowd and cars at the scene, and Bosco nabs the man he saw in the crowd the night before. The man turns out to be a fire buff, but Faith and Cruz's work bears fruit and they find their arsonist -- the son of Doug Maple, an NYFD arson investigator. A depressed Sully is still on leave, drinking too much, and sleeping on the couch at Ty's and Carlos' apartment; Doc connects with an attractive

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 is stunned when he discovers that the company paid the charity for whom he posed for the picture $10,000 for the right to use the picture, and that 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 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, Maritza, and a very pregnant Linda Barnes from the inferno, but Lettie Cruz succumbs to her drug binge 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; Maritza and Bosco's relationship goes to a new level when he attempts to comfort her on the lost of her sister; Kim finally testifies before the review board and stands up for Carlos.

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 job performance 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 R.M.P. and seeks advice from a union rep; Carlos loses his job as part of the department's settlement with the West family.

Bosco and Faith chase after people who have stolen money from a crashed armored van. Kim meets a journalist. The girl who accused Carlos attempts suicide, and the truth comes out.

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.

Although Dade encourages him to keep quiet, Bosco tells Swersky everything that transpired with Maritza, Noble, the death of Willie G, and the shootout in Noble's hotel room, and confesses that he killed Noble after Noble pulled out a gun, Faith was shot by Maritza, and that he grazed Maritza's head with a bullet to keep her from killing Faith; wracked with grief that his wife has a bullet next to her spine, Fred attacks Bosco and threatens to kill him when he discovers that Faith became injured while she was helping her partner out of yet another jam; a critically injured Lt. Johnson, in excruciating pain and with only hours to live, begs Jimmy and Doc to ease his suffering; overwhelmed at the sight of Lt. Johnson's wife lashing out in heartbreak and anger, and her husband's horrific suffering and imminent death, Doc sadly helps out his boss one last time; Swersky has Maritza arrested when she refuses to tell him what happened during the shootout; Bosco learns that Noble was working f

On his last day on the street, Doc's guilt and grief over Alex's death emerges as anger towards everyone he encounters, especially Eugene, the new paramedic trainee whose place Alex took the day she died; Kim becomes frantic as she fears that she have been exposed to HIV after having unprotected sex with a drug addicted Noble, and Jimmy agrees to accompany her when she gets tested; Swersky goes to bat for Faith by creating the opportunity for Bosco to talk to her before she's interrogated by I.A.B.; Carlos is less than thrilled when he discovers that Kim is the new supervising paramedic and Jimmy has been promoted to take over Lt. Johnson's position; Bosco returns to work and faces a hostile reception from the squad for ratting out Maritza; Faith awakes to discover that she's paralyzed; Maritza refuses to let Faith off the hook for shooting her until Bosco tricks her into recanting her story; Faith thanks Bosco for keeping her out of jail and saving her job, and then tells him to get l

Yokas clashes with her mother over her recovery; Maritza is back on the job, but unhappy that she's back in the bag and handing out parking tickets; Ty and Sully discover a truck carrying sick illegal aliens and end up scouring the city to track down one of them who escapes after it's determined that the aliens have a highly contagious and potentially fatal disease.

Sasha, Bosco, Sully and Ty get on the case of a malicious rapper. Ty considers returning to law school with the help of Sully. Jimmy struggles with his new position and his relationship with his co-workers when he makes a big mistake during a fire drill. Faith gets a physical therapist.

As Carlos desperately searches for a bone marrow match for Kylie, he digs deeper into his own past and discovers that he wasn't abandoned by his parents, but was found clinging to his dead father's hand after a car accident; after a local station picks up the story, Carlos gets a call from a woman claiming to be his mother; Bosco and Monroe find themselves going after a small-time mobster putting the squeeze on an honest family-run linen company after the son of the linen company owner dies in a suspicious fire.

Bosco arrests a pedophile posing as a toy store Santa, and the grateful store owner returns the favor by helping Bosco and Sasha come to the aid of a man whose house is robbed of all his children's Christmas presents; after Sully and Ty save a young homeless girl from a fire, she rekindles Sully's Christmas spirit; Carlos receives the ultimate Christmas present when his brother arrives at the firehouse bearing the gift of being a perfect bone marrow match for Kylie, as well as the news of Carlos's real name and family history; Kim and Jimmy spend a romantic Christmas Eve together; Sasha's search for the perfect gift for her nephew gives Swersky the opportunity to play Santa.

Jimmy gets a promotion to a rescue squad in Brooklyn; despite their new captain's assurances, Doc suspects that he intends to close down the house; Sasha insists upon pursuing an investigation into the beating death of a hit-and-run driver after Maritza uses the confession of an innocent man as her stepping stone to an Anti-Crime reassignment; after Jimmy is trapped in a warehouse fire, Kim reassesses their plans for a future together; Rose's serves a customer at the bar who shares a past with Bosco.

Steeper exiles the paramedics to permanent fixed posts on the street, which upsets everyone on the squad except Doc, who refuses to let anything put a damper on his unusually upbeat attitude; Carlos is less than thrilled when Doc invites Christian to accompany them on a ride-along without getting the proper authorization; when Bosco goes after Nardo for his veiled threats against Rose, Nardo tries to set Bosco up to look like a dirty cop; Rose is fired after Bosco destroys poker machines owned by Nardo in the bar where she works; on the eve of her return to duty, Faith tells Bosco that she wants to repartner with him; Sasha's second thoughts about the plan she and Bosco hatched to repay Nardo for threatening Rose and attempting to frame Bosco turn out to be on target when Nardo flees after murdering two men; Doc and Sasha hook up after Doc throws a big party at his house for his co-workers.

Steeper continues his by-the-books command style and goes head-to-head with Kim when Doc doesn't report for duty on time; Sasha can't find her off-duty weapon the morning after Doc's party; Faith returns to duty at the front desk despite Fred's wanting her to remain on disability, and discovers that Bosco has lied to her about Swersky's not allowing them to be partners; a panicky Nardo kidnaps Rose and then Bosco in a futile attempt to prove that he wasn't a rat, and makes a shocking choice when he realizes that his days as a mobster have come to an end; to the horror of the squads, Doc takes extreme measures to prevent Steeper from closing the house, and forces Carlos and Kim to risk their lives to do the right thing; Sully returns a favor by reaching out and saving his friend's life in Doc's hour of greatest need.

Distraught over losing an appeal to her suspension, Sasha gets into a car accident that claims the life of a young child; Sully and Ty take the L.S.A.T.; tensions flare between the cops and the firefighters when Maritza goes after J.D., the newbie firefighter, who turns out to be an ex-cop who ratted out Maritza's former partner for stealing drug money; Faith and Fred are still at odds over her return to work; Walsh is promoted to lieutenant; Ty watches over a devastated Sasha, who's racked with guilt over the car accident, Doc's shooting spree, and the events surrounding the deaths of Tanzi and Nardo; J.D. gives Faith and Bosco important evidence he discovered as he put out the fire resulting from Sasha's car accident, which leads the cops to uncovering the basis for the accident and exonerating Sasha.

Wary of Lester Martin, the high-priced lawyer his father has found for Mikey and the deal he's attempting to broker, Bosco warns his brother to stay away from Maritza, but Mikey decides to disregard his brother's advice and makes a deal to become her informant; for good measure, Bosco threatens to kill Maritza if anything happens to Mikey; Sully teases Ty about his budding relationship with Sasha; Faith and Bosco strike a deal with Laura, who also has no love lost for Maritza, to protect Mikey by helping her nab the drug dealers before Maritza gets to them; J.D. offers Kim a ride home, but stops off first at a rave that both Anti-Crime and Narcotics have staked out, thanks to information Mikey gave them; when some bad ecstasy begins to take a rapid toll, the paramedics call for backup, which prompts Maritza and her detail to storm the building; after an arsonist lobs a Molotov cocktail into the crowded building, Faith and Bosco give chase and capture him, while the firefighters rescue

Faith begs Fred to return home, but he refuses for a reason that infuriates his wife; Bosco turns a cold shoulder to Maritza's attempts to offer her condolences; Carlos is spectacularly unsuccessful in his attempts to hit on Grace; on the day of his son's funeral, Donald Mann exacts his revenge with the help of a dirty cop by planting bombs designed to kill the police officers he holds responsible for the death of his son; after Mann's lieutenants force a man to crash a car carrying a live bomb into the funeral home where Mikey's wake is being held, Grace takes charge and goes out of protocol to save Rose's life, and Dr. Fields later swears to have her job for it; Kim's decision not to enter the funeral home while the bomb is still live stems not from cowardice, but from maternal instincts; when Mann discovers that some of his intended targets survived the bombings, he sends machine-gun wielding minions into the hospital to finish off the job.

Internal Affairs drops the bomb on the envelope-pushing Detective Cruz as she is taken away and struggles to survive in jail, while Captain Finney drills Detective Yokas for information that will nail Cruz - but the torn cop secretly knows that she pulled the trigger on a career criminal that frames the case against Cruz. Officer Sullivan reveals more about his running feud against Finney and his rookie son. Carlos and Levine keep getting called to help a suicidal woman. Bosco's condition changes.

Ty rats out Sasha to the squad after Finney refuses to transfer her out; an action star doing research for his next movie goes on a ride along with the firefighters, and Stu quickly discovers that his boyhood hero is a failing alcoholic looking for a chance to revive a dead career; Brendan offers to ride with Sasha when everyone else refuses to do so, which leaves Ty and Sully partnered again; the retired detective who gave Sasha the real I.A.B. file on the death of Ty's father is found murdered by a police-issued bullet; Sully decides to testify against Finney; in pursuit of a drug dealer who shot an eight year old girl, Sasha and Brendan are injured, but the other units in the sector fail to respond to their calls for help until Ty and Sully finally relent and come to their aid.

Everyone in the 55th Precinct faces their worst fears when terrorists are discovered to possibly be building a dirty bomb. Carlos and Levine face trouble in their relationship. Captain Finney decides to end his life, rather than surrender himself for the murder of Ty Davis Sr. Brendan and Davis try to cover it up.

Cruz teams up with Rice to track down the terrorists associated with the possible dirty bomb.

Faith negotiates the end of a live on TV hostage situation. The leader of a vampire cult holds Emily hostage until Bosco saves the day. Cruz attempts to negotiate a deal with a gangbanger to end the war on the 55th Precinct, but instead, he organizes his troops to attack.

The series concludes with the gangbangers taking out their assault on the 55th Precinct. After some grenade explosions, the precinct is destroyed. Cruz knows that Marcel Hollis is behind the attack, and she takes his life, as well as her own. Carlos proposes to Holly, and they are married. Everyone receives their reassignments, and Sully retires. In the last few moments, Sully narrates a look into the future.