Dr. Benton has to deal with the aftermath of his mother's fall and crosses the line with the surgical attending when he insists on scrubbing in for her operation. Dr. Greene deals with Jodi O'Brien who is two weeks away from giving birth. With the obstetrics attending unavailable, he decides to try to deliver her baby in the ER, with tragic results.

Dr. Greene is still having trouble dealing with cases in the ER and the new Chief of the ER is growing increasingly concerned. Greene also faces a difficult peer review to examine his handling of the Jodi O'Brien case. Dr. Benton takes on the difficult task of telling his mother that she must be placed in a home with full-time care. Susan's very pregnant sister Chloe returns to live with her. Dr. Ross deals with the case of a young girl with a heart condition while Ross and Carter encounter a patient who refuses treatment for tuberculosis. When Benton asks Deb Chen and Carter to submit their procedures book in a few days, Deb feels she has to get a few more procedures under her belt if she's to best her fellow student. Unfortunately, her eagerness leads to near tragedy for a patient.

Greene finds his marriage falling apart and is concerned at how little time he's spending with his daughter. He also treats an eight week old child with a heart murmur who requires surgery. Susan tries to get her pregnant sister Chloe to take her pregnancy seriously, but her head isn't quite into it. Benton tries desperately to find a surgeon who will operate on a 16 year-old with a severe brain aneurysm that could burst at any time. He's also concerned at his mother's care and is growing ever more attracted to Jeanie Boulet. Doug Ross' commitment to Diane Leeds gets more serious when he agrees to be an assistant coach for her son's little league baseball team.

While victims of a gang shootout are being brought in, Carter is late and a new group of third year medical students arrives.

Benton tries to save someone who, according to the other surgeons, can't be saved while the ER gets crammed with pregnant women.

Race relations become an issue in the ER when Mark Greene treats two injured teenagers, one black and the other white, and assumes the black kid was a drug dealer. It turns the white kid was the drug dealer and the black kid is a high school basketball star and an innocent bystander. When the black student's older brother confronts him, he begins to question his own impartiality. Carol Hathaway helps a young woman who was drugged with Rohipnol and raped. Benton gets an interesting offer from Dr. Hicks. He also learns that Carla Reece has been admitted to the hospital. Dr. Carter treats a woman with a serious condition but he seems to be the only one who sees it. Mark Greene's daughter ends up spending the day in the ER when her mom has to rush to Florida to deal with a family emergency.

Benton tries to find out if everything's OK with Carla's baby. Carter tries to get a man operated, despite the fact Anspaugh thinks he will die no matter what.

Jeanie asks Greg to help Al get into a special AIDS-program at the hospital. Olbes brings in her grandfather, who had a stroke.

It's Carol's birthday, Mark is returning to work after being assaulted and Carla goes into premature labor.

On Thanksgiving Day Carol goes into labor. She's able to get to the ER only thanks to Luka's help. She delivers the first baby in the ER, but the second causes some trouble. Greene leaves Elizabeth to deal with his father and daughter, as he rushes to assist Carol.

As the result of a school shooting, Kovac and Benton care for the gunman and his victims. Abby discovers that Carter has been illegally injecting pain relievers. Greene and Weaver confront Carter about his problem, and Weaver orders him to enter a drug rehabilitation center or leave the hospital permanently.

Dr. Carter struggles with his drug dependency; a custodial strike leaves the ER cluttered with garbage; a riot at a high-school football game leaves several wounded.

A young couple cope with their baby being premature; Greene and Corday struggle with their relationship.

Chen gives birth, but insists on breastfeeding the infant before she gives it to the adoptive parents. Greene and Corday consult a brain specialist in New York City who believes the tumor can be safely removed. Stressed and tired, Carter impulsively swallows two painkiller pills but intentionally vomits them. He confesses to Abby.

As the new director of diversity, Benton studies medical school applications and discovers that his own academic record did not qualify him--he was admitted because of affirmative action. Weaver feels uncomfortable amongst Legaspi's lesbian friends. Carter treats an unvaccinated child who contracted measles.

On Thanksgiving Day, a helicopter crash outside the ER leaves several injured. Alex tries to bring Sam and Luka together.

Ray objects when a surrogate mother in labor endangers the baby's life by not wanting to have a C-section. Meanwhile, Sam tells Luka that she and Alex are moving out; Pratt meets his half-brother and -sister; and Abby makes a difficult decision about a young boy.

Neela treats a religious teenage girl who turns out to be pregnant. Abby and Kovac struggle to figure out what to do with her unexpected pregnancy.

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.

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.

Abby deals with her upcoming reunion with Luka in Croatia, a heart transplant patient is admitted when her body rejects the new heart, and a new doctor ruffles feathers.

Abby returns to work; Luka applies for a job elsewhere; the reason behind a brash doctor's being at County is revealed.

The Last One Before Christmas Break. The one in which Frank and Drs. Sanchez and Wade accidentally get brownies with cannabis in it. The one with the Christmas party. Archie's cousin brings Archie's deceased father's storage container to the ER bay. An injured pregnant Latino woman is brought in. There is something wrong with her baby?. Plus, the Immigration Office wants to deport her.

The police wheel in a casualty of a drug deal-turned-shoot-out. They also bring in an injured woman who was the shooter, plus a pair of wounded brothers who were shot by the man who was shot dead. A 13-year old girl with sickle cell disease is brought in because of abdominal pains; Neela takes her case while Tracy learns from her. Banfield's pregnancy test is negative, which leads to a discussion with her husband and a visit to a specialist.

A girl who was hit by a car while riding a bicycle is treated in the ER. When her boyfriend turns up, it seems it may not have been an accident. While a lottery has made millionaires of several nearby convenience store workers, Dr. Banfield and her husband are at the fertilization clinic hoping for their one in a million chance. And as an older woman is brought in assisted by her on-again, off-again husband, three love stories continue in the ER: Dr. Morris meets policewoman Diaz again, Sam discovers that Tony has been seeing Daria, and Neela plays it cool with the returning Dr. Brenner.