Mark finds himself manning a very crowded ER on his scheduled night off, filling in while Doug is out with whiplash and Susan meets with her lawyer. He tries to juggle hunger pangs, 40+ patients in the waiting room and a never-ending stream of traumas.

Una explosión en la bodega de químicos envía a varios trabajadores de la sala de emergencias a la sala de emergencias, poniendo a todos en peligro cuando descubren benzeno en el piso. La sala de emergencias es evacuada por Carter, cuando Weaver es afectado por el tóxico. El equipo de materiales peligrosos se reporta en el hospital. Hathaway y Ross quedan atrapados dentro de un elevador con una pequeña con problema renal que necesita dialisis. Trabajan fervientemente por mantenerla con vida.

During a paramedic ride-along, Carter is forced to drive the ambulance while fleeing a riot scene and inadvertently runs over a teenage boy. Later, a paramedic is shot by an angry mob looking for the driver of the ambulance. Carol is despondent following Doug's departure. She later discloses that she's pregnant. Kerry is intrigued by an injured pro wrestler and his relationship with his father. Lucy tangles with an Asian family that requests their matriarch not be told of a cancerous tumor. Jeanie turns down dates with both Dr. Baker and Reggie, telling each she's seeing someone else.

Lucy's patient finally gets a heart transplant but does not survive. The transplanted heart will now go to another recipient. Greene interferes in a gay domestic situation. Corday tricked her patient who murdered several women and now he's being transferred to a county jail.

Even though he suffers from intense pain due to his stabbing injuries, Carter returns to work and prescribes a controversial procedure for a suicidal patient. Greene tries to convince his father to undergo cancer treatment.

Greene flies in a helicopter to a remote area of Indiana to rescue a heart transplant patient. The helicopter develops problems, and Greene arranges for paramedics to transport the patient to County. Because Weaver is gone for the day, Romano appoints Benton in charge of the ER. Kovac is plagued by the death of the mugger.

A demented patient causes a shootout in the emergency room. After terrorizing people in the ER with a gun, she gets shot by a policeman. She soon dies. Benton later discover her dementia was caused by an aftereffect of his surgery that he and Cleo should have detected. Carter pursues a cute intern.

Lewis faces a hectic first day back at County General. Benton and Roger become frantic when they can't locate Reese. Carter's grandmother is brought to the emergency room. Carter and Abby deal with inept medical students.

Peter Benton continues his court fight against Reese's stepfather, Roger, who seems to have the upper hand. When a woman is accidentally shot during a gas station robbery, Dr. Corday tries to convince the husband to let them harvest her organs. A 15 year old boxer is brought in with a head trauma after sparring with his older brother. Newlyweds are having trouble when she constantly breaks out in a rash; Carter thinks he knows the cause.

Just when the ER is understaffed and swamped, two children who were brought in turn out to have full blown smallpox. The entire ER must be locked down. The staff needs to improvise while they battle not only the disease but also frayed tempers.

On a busy Halloween night, Carter and Abby are the only staffers in costume when victims of an apartment building fire pack the ER. Corday takes on a new med student for a surgical rotation - Paul Nathan, who suffers from Parkinson's disease and decided to pursue medicine after being diagnosed. Despite a difficult first day, both professionally and medically, Nathan makes a difficult diagnosis. Romano's rehab lags behind his expectations, and he begins to doubt his role in surgery is no longer an option. In a moment of personal weakness, he tries to express his ...

Dr. Weaver bends the rules and treats the Alderman's lover for syphilis. Dr. Kovac's patient claims she was sexually abused at a boot camp for troubled youth. Dr. Carter treats a women with a nasty personality.

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

After being shot at, Pratt, Jing-Mei and Elgin are trying to get of their sinking car. Sam took Alex with her while fleeing for Steve, Kovac is considering to go after them. Abby wants to go to bed since tomorrow is her first day as a doctor, but is thwarted by Weaver, whose custody battle might take a dramatic turn. A young drug-dealer is brought in with "a foreign object" in her tunnel of life.

A wounded police officer's teenage son must make a life or death decision. Abby tries to convince a girl needing appendicitis surgery to stay at County, but her fathers wants her transferred to another hospital.

A woman on a hunger strike refuses treatment until the INS give her son another deportation hearing. Abby searches for proof when she suspects a patient is the victim of elder abuse.

Dr. Nate Lennox, a former professor with ALS, is brought in as the progression of his disease is chronicled through his own flashbacks as he is treated by each of the doctors at one point. As Lennox wants to give up, Abby fights to convince him to keep on fighting.

Curtis Ames, a carpenter who suffered a stroke under Kovac's care, sues him for malpractice. Kovac and Ames square off in court as each man's recollections of Ames' treatment are recounted via testimony and flashbacks. Meanwhile, Abby returns to work and must adjust to the dramatic changes in her life, and Pratt's early morning trip to the barbershop results in a new awareness of community need. Also, Abby and Pratt try an unconventional method for treating a heart patient and Neela tries a risky procedure which doesn't sit well with her chief.

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.

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.