Weaver, Kovac, and the other doctors work frantically to try to save Jerry and a pregnant Abby, who were both critically injured during the shootout that left the ER in shambles. Meanwhile, Sam tries to escape from her ex-boyfriend and his criminal accomplices as they head north, but things quickly turn violent.

As Abby and Luka cope with their newborn's life and death struggle, the couple is shocked to receive a surprise visitor: Abby's mother Maggie. Meanwhile, Sam fears the prospect of criminal charges; Neela discovers that Tony Gates will be joining the ER team as an intern and Morris gets his job back while Weaver gets demoted.

Gates is assigned to the case of a closeted gay man whose partner clashes with his family; Neela meets her new surgical chief, Dr. Crenshaw; and Pratt must cope with the flood of new interns.

Abby and Kovac discover both the joys and difficulties of raising a newborn; Morris is wrongfully accused of being a child molester; Pratt has his trial-by-fire when he has to handle the ER alone, juggling multiple traumas, teaching duties and a troublesome intern. Neela continues to be the target of her difficult supervisor, and Sam discovers her sons latest extra-curricular activity.

Due anni fa, un carpentiere di nome Curtis Ames ha subito una serie di complicazioni mentre si trovava sotto le cure del dottor Kovac. Ora ha deciso di citare il medico per negligenza professionale. In tribunale vengono ripercorsi gli eventi e sentite le testimonianze di tutti coloro che hanno collaborato al caso dell'uomo di colore. Luka è preoccupato dalle conseguenze provocate dalla causa e da un possibile verdetto sfavorevole. Abby ritorna a lavoro e deve subito affrontare i cambiamenti che la sua vita ha appena subito. La mancanza di equipaggiamento costringe Pratt, Abby e Neela ad una rischiosa procedura su di un paziente. La mattinata trascorsa da Pratt dal barbiere si trasforma in una nuova presa di coscienza dei bisogni della comunità.

Due pazienti arrivano al Pronto Soccorso in seguito a un incidente stradale. Luka e Ray si occupano del motociclista e scoprono un segreto riguardante la salute del paziente. Luka incontra nuovamente l'ex paziente che l'aveva citato in giudizio...

A belligerent young man with the flu turns out to be more than he seems, and presents a challenge to Morris and Sam when he refuses treatment. Abby's chance encounter with Curtis Ames leaves Kovac uneasy. Meanwhile, Pratt discovers a local church's risky drug exchange program, Neela and Gates square off, and Weaver gets an interesting offer.

A mysterious illness leaves little hope when a group of homeless kids enter the ER and one of them believes that Neela is a guardian angel in blue; Abby and Kovac clash over a possible case of domestic abuse; Pratt makes a shocking discovery about his brother, and Weaver is unexpectedly called into action when her television appearance becomes a real emergency.

È il Giorno del Ringraziamento e lo staff si prepara come sempre a festeggiare la lieta ricorrenza. Abby si occupa del volo di trasferimento di una paziente anziana, durante il quale, insieme all'equipaggio, finisce con il trovarsi nel bel mezzo di un grave incidente occorso ad un autobus. Luka è sempre più ansioso a causa della costante presenza di Curtis Ames. Gates cerca di fare colpo su Neela preparandole una cena messicana, ma i due vengono interrotti dall'improvviso rientro a casa di Meg e sua figlia. Pratt si rivolge a Kerry dopo aver scoperto la verità su Chaz.

Kovac and Gates treat a girl who appears to have been assaulted. When the police are no help with Ames, Kovac decides to confront the problem himself; Morris and other doctors work on a patient with an ice pick in his ear. Meanwhile, Ray tries to keep his new relationship a secret and Pratt can't fully deal when his half-brother officially comes out. Also, a new male nurse arrives.

It's Christmas in the ER. A homeless boy sends Gates and Ray on a mission. Meanwhile, in the ER, Neela oversees an unusual kidney transplant case; Sam takes a stand when a patient is dumped in an alley by another hospital; and Morris plays Santa for a special girl and learns the meaning of Christmas.

Pronto soccorso di Chicago. Un gruppo di medici alle prese con le emergenze più gravi, ma anche con i problemi e le speranze della vita. Una serie tv che è diventata un cult. Più tardi, viene a sapere che il caso è oggetto di un indagine e così si vede costretto a confessare tutto a Luka, proteggendo nel contempo il ruolo avuto da Hope nella faccenda. La vita privata di Gates interferisce con il lavoro del medico. La scomparsa della carta di credito di Morris sembra preoccupare Sam: il responsabile del furto è infatti Alex.

Kovac reacts negatively when he sees Abby giving extra attention to a patient; Ray and Gates clash over a patient, pinning Neela in the middle; and Ben takes things to the next level with Sam. Meanwhile, Pratt is under investigation and Weaver says a final goodbye to the ER.

Kovac finds himself in a tense confrontation with Curtis Ames, and Abby must act to protect her family. Meanwhile, Neela and Gates rush to get Meg to the hospital while Sam's new home is soon under threat from fire.

Abby and Sam try to treat an obnoxious, aspiring comedian with mysterious symptoms; Pratt must defend his actions in front of the medical board; Neela scrubs in on a kidney donor transplant; and Morris, as the lone attending, must run a busy ER. Also, Kovac gets a surprising proposal from Abby.

Luka, Sam e Gates si occupano di una paziente che sembra soffrire di una crisi epatica, disturbo che potrebbe essere il risultato di un tentativo di suicidio. Luka affronta Gates quando il giovane tenta di mentire su di un documento medico che potrebbe garantire ai figli della paziente l'assicurazione sulla vita della madre. Abby si interessa al caso di una coppia ferita nel corso di una bizzarra cerimonia Wiccan. La dottoressa viene a conoscenza del suo futuro tramite un paziente con problemi neurologici che si atteggia ad indovino. Neela affronta l'ennesimo problema etico quando scopre che un donatore di reni sta per essere profumatamente pagato dal ricevente. Ray cura una cheerleader che è stata ferita durante una sorta di iniziazione. I problemi di Alex continuano ad intromettersi nella vita lavorativa di Sam.

A blizzard strands a family in the snow and Abby and Pratt quickly try to save the family. A gang shooting challenges Morris and Pratt. Meanwhile, Kovac and Abby begin making wedding plans, but their engagement might not be very secret; Gates struggles with the reappearance of his father and the possibility of losing Sarah; and Neela becomes jealous when Dubenko brings in a new surgical intern.

It's Sam's birthday, but she finds it hard to be away from her son Alex. Meanwhile, Sam meets a photographer taking pictures of a terminal patient and she gives Sam a new perspective on life. Dubenko's new surgical intern unsettles Neela during a trauma; Gates is shadowed by a new and nerdy intern and later must tell Sarah the truth that he may be her biological father. Also, Morris and Hope annoy Kovac and Abby when they try to help with their wedding preparations.

Kovac and Gates deal with a hopeless father whose son succumbs to heart failure; Pratt tries to resolve the tension between him and his brother; an Armenian man tries to be a good samaritan but ends up crashing near the ER; Abby sneaks in baby Joe when she worries his sickness may be worse than it seems; Also, Sam injures the instructor of a self-defense seminar.

What is suppose to be a departmental dinner organized by Kovac turns out to be the surprise of a lifetime for Abby when she soon learns it's a surprise wedding, secretly planned by the eager groom. Meanwhile, at the wedding, ER staffers enjoy themselves with music and booze while Neela finds herself the center of unexpected attention between Gates and Ray, which leads to a drunken fight and a shocking conclusion.

Dr. Kevin Moretti, an ICU specialist bent on change, joins the ER team. Change comes elsewhere as Luka and Abby adjust to being husband and wife, Pratt tries to be a new man to his lady friend, Morris and Hope take things to the next level, and Ray goes missing. Later on, Luka gets a troubling phone call.

Season Finale: Luka postpones his honeymoon, leaving Abby, Joe and the ER behind to begin a different journey. Meanwhile, it's Moretti's first day as Chief of Emergency Medicine, and everyone feels the effects of his style, especially Pratt and Morris. Neela learns of Ray's fate, then joins an anti-war rally and finds herself in a dangerous situation. Gates faces a crisis on the home front.