Abby wakes up after the ambulance explosion and realizes that she has a broken wrist but quickly rushes to check on the others in the ambulance. A mother and daughter are also rushed in from the explosion and Abby misdiagnoses the case. Meanwhile, Morris and Neela struggle to keep up with the injuries sustained from the explosion.

Dr. Banfielda 's arrival and tough attitude causes the whole ER staff to feel defensive. Gates and the new interns fight to save the life of a terrorist while risking their own lives. Neela finds an unlikely advocate in her fight to get Dr. Dubenko back on the surgery staff.

Neela is upset to think she had learned about Abby's good news second hand. New Chief Catherine Banfield and Abby knock heads on how a gunshot victim should be treated in the ER. Sam receives help from Abby as she faces the nurses disciplinary board.

Banfield heads out for a cup of coffee and is caught off guard when she is mugged. Meanwhile, Dubenko is placed back on the surgery team thanks to Dr. Brenner; Banfield and Gates believe the injuries of a gymnast who claims to have fallen are really due to a family member; and Gates learns Sarah got her tongue pierced without his permission.

Gates feels neglected as Sam spends all of her time studying for her upcoming pharmacology exam. Meanwhile, a stab wound victim comes into the ER following a vicious school fight and Brenner takes it upon himself to find out what really happened. Later, Morris surprises Neela and Gates finds himself locked in a stairwell with a young boy on Halloween.

Morris decides to teach Chaz various risky medical procedures, much to Banfield's dismay. Meanwhile, Gates oversteps his bounds with Sam.

Dr. Banfield sets out for a run to clear her head but soon finds herself attempting a rescue of a 3 year old girl who is drowning in a nearby lake. While trying to save the girl, Dr. Banfield has flashbacks to a time when Dr. Greene cared for her son at County. Gates tries to help a homeless war hero by pulling a few strings around the ER. Meanwhile, the interns continue to struggle in keeping up in the ER.

Gates obsession with a homeless war hero has Sam frustrated. When the whole surgery department gets named in a lawsuit, Neela becomes upset at her intern who caused the suit. A husband and wife come into the ER after an attempt was made by someone to burn down their home. Brenner gets physical with a patient after losing his cool.

Neela is in court to give her testimony over the death of one of her patients who bled out. Alex and Sarah get in a horrible car accident after going to a party against Sam's wishes. Meanwhile, Morris and Banfield are in Nebraska for an ER conference and become snowed in and stuck.

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.

A drug deal gone bad causes Banfield to treat two brothers in the ER who are seriously injured. Gates becomes upset with Sam after she fails to inform him that Alex was being released from the hospital. After treating a girl with sickle cell anemia, Neela considers changing her specialty to pediatric surgery. Meanwhile, Dr. Banfield and her husband makes a critical decision concerning their future together.

A bizarre recurring dream has Neela reliving the crazy day in which she treated a girl who was suffering from sickle cell anemia. Gates' patient injured himself when he jumped from a window while asleep. Meanwhile, Neela goes in for an interview concerning a new attending and is shocked when she sees Dr. Elizabeth Corday there.

Morris treats a child who was hit by a vehicle while riding her bike. Meanwhile, Gates can’t stop thinking about Sam, and having learned that Brenner has returned from Australia has Neela all nerved up.

Dr. Morgenstern makes a return to County general when his former mentor is felled by a serious illness. Meanwhile, Sam receives an unexpected visit from her sister. Plus, Gates and Morris help out an elderly man who was beaten on the streets, and Brenner's patient is affected by a shocking problem.

Brenner searches for someone to take care of the daughter of a severely injured patient. Morris takes on an insurance company when they refuse to pay for a 78-year old man's necessary treatment. Meanwhile, Neela informs Brenner of her offer from another hospital in North Carolina.

The staff is surprised when Dr. Green stops by for an unexpected visit. Meanwhile, Gates treats a groom who may have caused his own respiratory distress by hunting for mushrooms. Elsewhere, Dr. Banfield tries to convince her husband that they should try to have another baby.

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 arrives in the ER to interview staff for a documentary on emergency medicine. Morris' girlfriend is shot in the line of duty and is rushed into the ER. Meanwhile, Neela worries that her relationship with Brenner is lacking enough communication; and Sam tries to reconnect with her mother.

Neela and Sam are stunned when they find their transplant plane has left without them. Dr. Carter gets a surprise from an old friend as he waits on his transplant. Meanwhile, Dr. Banfield bonds with a child abandoned in the ER.

It's Neela's last day in the ER, but everyone seems to have forgotten that she is leaving. She proves she is ready to be an attending by arguing with Dr. Dubenko over two surgical cases. Meanwhile, Brenner reflects on his past.

Doctors and nurses from the ER help out at a camp for children who have had open heart surgeries. A woman returns to County for the baby she previously abandoned there....

John Carter opens his new medical facility and his former colleagues and friends come to show their support. Meanwhile, Dr. Gates treats a teenager with alcohol poisoning after playing a drinking game. Sam is surprised when she receives a birthday present. Dr. Rachel Greene starts her first day as an intern, in the same ER her father worked many years before.