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.

Doctors take care of 24-year-old Gloria Ortiz who is 8 months pregnant. The woman fell during an immigration raid at a tie factory and started getting contractions. Coburn discovers that the baby has a mass in the neck and head area… maybe cancer? Immigration agents come to the hospital to take Gloria into custody. Banfield has Morris do paperwork instead of seeing patients. Frank plans to dress up as Santa for the Christmas party. Neela has no intentions on going to said party claiming that last year turned out bad since Morris pinched her butt and Frank almost threw up on her. Sam pushes Dubenko to extubate Alex today instead of tomorrow. Neela is at the center of a malpractice suit.

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 in the ER and Neela seems to be under the spell of Dr. Brenner. Gates treats a bizarre mushroom hunter that comes in on his wedding day with breathing problems. Banfield refuses to give up on having a baby but is having trouble convincing her husband of her plan. Neela gives a little girl great news about her mother’s heart transplant surgery but is disappointed when a critical mistake is made. Meanwhile, Dr. Carter makes a surprise return to the ER.

After getting frustrated with In Vitro Fertilization Dr. Banfield and her husband decide to try an adoption agency to fulfill their dreams of having a family. Dr. Carter quickly tries to jump back into working at County but struggles with all the new procedures and technology. Sam is shocked when her mom comes into the ER 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.

It's Neela's last day and everyone in the ER seems to have forgotten that she is leaving. Neela proves she is ready to be an attending when she and Dr. Dubenko argue about the treatment of two surgical cases. Meanwhile, Brenner has an epiphany about his troubled past.

Many of the ER doctors and nurses help out at Camp Del Corazon, a camp for kids who have had open heart surgery. Working along side the camp counselor, Morris and Brenner make a huge impact on several kids at the camp. Meanwhile, Dr. Banfield and her husband feel their adoption dreams slipping away when a young mother comes back for the child she abandoned in the ER.

Gates works on a young teen brought in with alcohol poisoning after playing a deadly drinking game with friends. Dr. Carter opens a new medical facility for the underprivileged in Chicago and some old friends from County General all come to show their support. It’s Sam’s birthday and Alex and Gates surprise her with a special gift. Meanwhile, Carter works with an intern to save a mother in labor with twins.