Weaver cares for a Katrina survivor who's reluctant to having surgery on her foot; budget cuts force Luka to make a difficult personnel decision. Also, Gates' home life intrudes on the ER; and Pratt and Hope are shaken after a patient in their care dies needlessly.
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.
Kovac and Gates find themselves with a moral dilemma when a woman comes into the ER with acute liver failure; Neela finds herself questioning what is right when Manish decides to give up a kidney to a complete stranger. Meanwhile, Ray fights to get to the bottom of a cheerleaders accidental fall; Abby gets a prediction for her future; and Alex's troubles continue to intrude on Sam's work life.
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.
In 12 hours, the ER will shut down. As Kovac is under pressure to take care of the patients before the final hours, he makes a pivotal decision about his future. Meanwhile, Sam befriends a photojournalist who returns only this time she's terminally ill; Pratt is concerned when his brother ends up in the ER drunk; Morris confronts Gates when he ignores his orders and angrily sends him home while Gates tries to defend his actions.
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.
The ER reopens with new changes. However, the ER is not the only thing that's changed; Kovac and Abby adjust to being newlyweds; Morris and Hope enjoy themselves at the honeymoon suite; Pratt attempts a change for a woman; Neela worries when Ray goes missing; Meanwhile, there's a new doctor in the ER and he means business; and another change may come when Kovac receives a phone call.
The ER is now in the hands of a new chief, Dr. Kevin Moretti, who is bent on major changes. Meanwhile, a phone call leads Neela to a hospital where a major shock awaits her, and a final farewell from a friend and colleague. Gates urgently goes home to stop Sarah from being taken away from him. A drug-addicted Iraq War veteran baffles Morris and Sam. Also, Kovac postpones the honeymoon and says goodbye to Abby and his son, for the meantime, while he travels to Croatia to visit his ailing father.
Abby, Pratt and Morris clash with Moretti's strict new ER procedures as victims of an anti-war rally roll in, including Neela. Gates manhandles a patient he suspects set off the explosion that disrupted the protest. A worried Dubenko lets his emotions for Neela take over during Neela's surgery. Meanwhile, the rest of the staff worry over Neela's condition.
Patients include a Pregnant teacher whose student/lover was critically injured while driving; a man who is hiding a gunshot wound and a brilliant young boy who knows he is dying, but hides it from his mother. Dr. Moretti continues to remake the ER to his liking, Neela is recovering, Luka's absence is reinforced (back in Croatia and not coming back) and Sam may be starting a new relationship with a police officer.
Abby and a distracted Morris work to save two auxiliary cops brought in with gunshot wounds. Pratt treats a teen wrestler with severe vomiting, but the problem is much more serious. Sam worries over her new beau Litchman. Gates tries to help a young boy in the ICU with a deadly disease. Also, Dubenko visits Neela while she babysits baby Joe.
Moretti reassigns Gates back to the ER and treats a couple involved in a car accident. Morris prepares to take his written board exams. Neela is assigned a young genius intern. Kovac plans to extend his stay in Croatia while Abby struggles with single parenthood.
Moretti brings in new attending Skye Wexler to help with the patient load. Morris and Pratt cram for the medical board exam. Gates treats a returning patient from the ICU whose condition has worsen. Sam tends to a teenage girl who is feeling neglected by the staff. Neela's intern, Harold, seeks her advice on a personal matter. Abby struggles with her relapse.
The city suffers power outages during an unseasonably hot spell. Nursing-home patients are brought into the ER suffering from hyperthermia. Abby and Pratt disagree on the diagnosis of a fussy baby. Abby falls back to old habits and quickly down spirals to rock bottom on a night she'll forever regret.
Morning shift begins. The night shift treated 142 patients - a new record. Dr. Morris is confident that by the end of the day the ER can set a new record of 300 patients. Frank reminds him that there has never been more than 250 patients in a day. Dr. Morris bets $300 that they can reach 300 by the end of the shift. Frank, Dr. Gates and Dr. Pratt each bet $100 against him. But will the game be fair? Also, when chaplain Dupree arrives announcing that she's doing a round of the hospital, holding blessing ceremonies and memorials, the guys are against it, except for Dr. ...