ER explores the inner workings of an urban teaching hospital and the critical issues faced by the dedicated physicians and staff of its overburdened emergency room.
Abby awakens after the ambulance explosion and rushes to check on Pratt; Sam and Gates rush to the scene; Morris and Neela struggle to keep up with Pratt's injuries.
Everyone in the ER is trying to cope with the loss of their colleague. The staff feels defensive toward the new Chief and her tough disposition. Gates and the new interns treat a bio terrorist, who has a lethal secret that endangers them all. Neela makes a great effort to get Dubenko back on the surgery staff, and gets help from an unexpected souce.
Neela is upset when she finds out Abby's good news second hand; the new chief, Catherine Banfield, and Abby disagree on how to treat a gunshot wound victim; Abby defends Sam when she goes before a nurses disciplinary board.
Banfield is caught off guard when a man tries to steal her wallet; Dr. Dubenko returns to the surgery team; a family member is suspected of hurting a young gymnast; Sarah gets her tongue pierced.
Sam's time is taken up by her studies for a pharmacology exam, leaving Gates feeling neglected. A school fight results in a stabbing, with Brenner treating the victim and trying to uncover the truth behind the story. Morris has a surprise for Neela. Gates gets locked in a stairwell with a quiet young boy on Halloween night.
Dr. Banfield is irritated when Morris takes Chaz under his wing and teaches him risky medical procedures; Neela is unhappy when Dr. Banfield undermines her authority with an intern.
Dr. Banfield takes a run to clear her head but finds herself trying to rescue a three-year-old girl from drowning in a nearby lake. Gates tries to pull some strings in the ER to help his homeless war hero. Banfield is reminded of her own experience at County with Dr. Greene caring for her son as she tries to save the young three-year-old girl from certain death. Meanwhile, the interns continue to struggle to keep up in the ER.
Sam gets frustrated with Gates when he gets obsessed with finding a homeless war hero. Neela is upset at her intern after he gets the entire surgery department into a lawsuit. A husband and wife come into the ER after someone tried to burn down their home. Brenner loses his cool with a patient and it gets physical.
Banfield and Morris go to the coffee shop at 3 a.m. and are served by 20-year-old Debbie who is six-months pregnant. The doctors treat someone with a heart problem and Alex. Chaz must look for a missing 7-year-old boy who saw his sister die.
Morris' father arrives at the ER's doorstep and leaves him an unwanted package. Sam wants Alex to get off the ventilator as quick as possible following his accident. Meanwhile, a woman is in danger of being deported despite her high-risk pregnancy.
Alex is set to be released from the hospital. Doctors treat African-American brothers Curtis Bennet, 17, who has abdominal pain and 10-year-old Quincy Bennet who has a knee injury. Both were injured during a drug deal that went terribly wrong. There's still some residual tension between Gates and Sam. A female patient in police custody doesn't want to be examed by Morris. A 13-year-old patient named Anastasia messes with Neela's love life.
Neela has a recurring dream; Gates tries to save a patient who jumped out of a window while sleeping; Neela is surprised to see Dr. Corday.
Morris tries to help a girl who was hit while riding her bike; Gates can't get over his feelings for Sam; Neela is flustered when Dr. Brenner returns from Australia.
Morris and Gates treat an older man who was assaulted on the street; Sam gets a surprise visit from her sister; Dr. Morgenstern visits County General when he discovers an old mentor is ill.
A mother is severely injured by a car accident in the ambulance bay; an insurance company frustrates Morris; Neela tells Brenner about her offer in North Carolina.
It's Valentine's Day. Dr. John Carter is back at the County. Brenner and Neela are getting closer. Dr. Banfield is having a hard time trying to have a baby. And Puck and mushrooms may not be a good combination.
Carter finds himself struggling with County's new technology and procedures. After becoming frustrated with the in vitro-fertilization, Banfield and her husband discuss adoption as an option. Sam's mother arrives in an altered state of mind.
A camera crew interviews the staff at County General for a documentary on emergency medicine. Morris’ cop girlfriend gets injured on the job and is rushed into the ER with gunshot wounds. Neela wonders why her relationship with Brenner lacks so much communication. Sam struggles to make amends with her mother.
Neela and Sam are shocked when they arrive back to the airport with transplant organs only to find that their plane has left them. Dr. Carter gets a surprise visit from an old friend while waiting for his kidney transplant. Dr. Banfield bonds with an abandoned baby boy that is left at the ER.
On Neela's last day at County, she has doubts as to whether she is making the right decision.
The ER doctors and nurses help out at Camp Del Corazon, a camp for kids who have had open-heart surgery, working alongside the camp counselor.
As Carter prepares to open a new facility for the underprivileged, some old friends/colleagues gather. Rachel Greene, Mark Greene's daughter, applies for an internship at County.