Carter is overwhelmed by patients from a rock concert riot. Benton's former girlfriend is killed in a car accident. Newly promoted to chief resident, Chen panics and misdiagnoses a patient. Kovac angers Abby by flirting with a waitress.

Dr. Susan Lewis arrives, looking for work in the Chicago area again. Greene hires her, over Weaver's objection. Chen nervously attends a risk management review, accompanied by the unforgiving Weaver, to discuss a patient who recently died under Chen's supervision.

Corday's ordeal, caused by the recent infection-related deaths of several of her patients, worsens when she is closely observed by a stern taskmaster. Corday is outraged when a county investigator accuses her of deliberately euthanizing the patients, who all happened to be elderly.

A new medical student, Michael Gallant, arrives in the ER. He's supposed to be working under Dr. Carter's supervision but his grandmother is unwell. Elizabeth Corday is convinced that other doctors are refusing to work with as a result of the mysterious deaths.

Dr. Carter, Abby and other staff of the ER are quarantined as the CDC investigate a mysterious, deadly outbreak.

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 ...

Corday clashes with new surgical resident Paul Nathan regarding his intervention into the treatment of a sickly young woman, Alison, who has signed a "do not resuscitate" order. Abby wonders about the erratic behavior of her visiting brother Eric, and feels conflicted over a nurse's official complaint against Kovac, Abby's former lover. Meanwhile, Pratt comforts Chen after a patient threatens her, and Corday suspects that an unconscious, 14-year-old female patient has been sexually assaulted.

Abby's troubled brother is missing. A car runs into a crowd of teen girls. The alderman with syphilis gives Dr. Weaver a promotion. Dr. Lewis looks forward to a blind date.

Dr. Romano seizes control of the ER and manages to offend everyone. Dr. Kovac asks Dr. Corday's help in the quest to bring a sickly Croatian boy to the U.S. for medical treatment.

Dr. Carter tries to prevent a grieving gang member from going after vengeance. Dr. Kovac races against time to save a Croatian boy's life. A baseball player gets treatment for a heart problem.

Ben Hollander is a distraught architect whose degenerating eyesight causes him despondent while a spirited new nurse, Samantha Taggart joins the staff. Elsewhere, disaster strikes when the doctors suspect a mother is abusing her child while Dr. Corday learns something shocking about the charismatic Dr. Dorset, and Dr. Archie Morris is overwhelmed by the chaos and grisly conditions of life in the E.R.

Pratt and Kovac clash over a miscarriage-prone young woman, Denny, who arrives to deliver a premature baby. Pratt wants to make heroic efforts to save the unborn child, while Kovac is adamantly against spending vast amounts of money to keep the forever sickly baby alive.

Morris streets a patient without getting a psych consult, and the guy steals a tank and heads for County. Gillian is visiting Luka, and Sam's not happy about it. Luka and Sam make up by the end of the day though. A 13-year-old boy has chlamydia. Frank has a heart attack. Corday plays the dating game, going out with two men.

Kovacs stops to help a woman and her son whose car broke down. Steve is getting close to Alex, and Sam panics. Abby is looking for her letter whether to see she passed her boards. Pratt shows off his new Chrysler. Elgin tries to build a connection between him and Pratt. Jing-Mei might be battered by her senile father.