ER (OV)

Abby recovers after the ambulance explosion and rushes to check on the other victims, but misdiagnoses a case. Meanwhile, Morris and Neela struggle to keep up with the wounded.

Dr. Banfield's arrival and tough attitude causes the ER staff to feel defensive. Gates and the new interns fight to save the life of a terrorist while risking their own lives.

When a gunshot wound victim arrives, the new chief and Abby butt heads on how to treat the patient. Abby comes to Sam's defense when she goes before a nurses disciplinary board.

After Banfield defends herself from a street criminal, she and Dr. Gates treat a young gymnast with suspicious injuries indicating abuse. Dubenko's back on the surgery team.

It's Halloween in the ER and there are all sorts of tricks and treats in store. Morris surprises Neela with an unexpected guest -- as former ER star SHANE WEST reappears.

COURTNEY B. VANCE guest stars in an episode when everybody seems to know best. Both Morris and Neela have authority issues with Dr. Banfield and Gates upsets Sam.

Trying to rescue a three-year-old girl from drowning in a nearby lake, Banfield is reminded of her own experience at County with Dr. Greene (ANTHONY EDWARDS) caring for her son.

Gates is obsessed with finding a homeless war hero -- much to Sam's chagrin. And while Neela's intern involves the department in a lawsuit, Brenner loses his cool with a patient.

Morris and Banfield are snowed in and trapped at an ER conference in Nebraska. Back in Chicago, Alex and Sarah go behind Sam's back and get into a terrible car accident.

Morris receives an unwanted package from his father at the ER doorstep. Meanwhile, Sam is anxious about getting Alex off of the ventilator after his accident.

Banfield treats two brothers that come into the ER. Meanwhile, Gates is upset with Sam over the fact that she never told him that Alex was released from the hospital.

After a crazy day trying to save a young girl with sickle cell anemia, Neela goes in for an attending interview and is surprised to see Dr. Elizabeth Corday (ALEX KINGSTON).

Love is a complicated operation in the ER as Gates can't seem to shake his feelings for Sam and Neela gets flustered when Brenner returns from Australia.

Dr. David Morgenstern (WILLIAM H. MACY) takes a trip down memory lane as he stops by County General and Sam's sister (SHANNON WOODWARD) pays an unexpected visit.

After a devastating car accident in the ambulance bay leaves a mother severely injured, Brenner struggles to find a family member to take care of the woman's young daughter.

On Valentine's Day, Neela falls under the spell of Dr. Brenner, Banfield refuses to give up on having a baby, and Dr. Carter (NOAH WYLE) makes a surprise return to the ER.

Banfield and her husband look into adoption, while Carter adjusts to a changed ER. Sam's mother (guest star AMY MADIGAN) comes into the ER in an altered state of mind.

The story of County General is revealed as a camera crew interviews the staff for a documentary on emergency medicine.

The ER doctors struggle to save two transplant patients when the transplant organs are stranded at the airport. And Carter gets a surprise visit from his old mentor Dr. Benton.

It's Neela's last day at County General and everyone in the ER seems to have forgotten that she is leaving. Meanwhile, Brenner has an epiphany about his troubled past.

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 (guest star TOM ARNOLD).

In the series finale, 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.