Carter and Lucy are discovered and the staff struggles to save them and go on with normal patient care.

Dr. Greene and Corday bond with their parents, Lucy cares for a patient with a psychotic break, and Valentine's Day celebrations in the ER end tragically for one of the students.

As the result of a school shooting, Kovac and Benton care for the gunman and his victims. Abby discovers that Carter has been illegally injecting pain relievers. Greene and Weaver confront Carter about his problem, and Weaver orders him to enter a drug rehabilitation center or leave the hospital permanently.

On Thanksgiving Day Carol goes into labor. She's able to get to the ER only thanks to Luka's help. She delivers the first baby in the ER, but the second causes some trouble. Greene leaves Elizabeth to deal with his father and daughter, as he rushes to assist Carol.

Greene prepares to bury his father. Chen worries about Carter's mood swings. After witnessing the interaction between a dying woman and her family, Hathaway realizes she wants her family together and flies to Seattle to join Ross.

Weaver reprimands Carter for doing a dangerous procedure without consulting Kovac. She also talks to Hathaway about Hathaway's lack of focus on the job. And while treating a 6-year-old patient involved in a minor car accident, Malucci and Cleo discover the girl has been sexually molested recently by her father.

Benton struggles with the idea of taking a DNA test to determine whether or not Reese is actually his son. As the signs continue to pile up, Kerry and Mark use a fake patient to convince Dr. Lawrence of his Alzheimer's. Carter has trouble persuading a woman from a nursing home fire to sign a DNR for her husband and later is asked to forge charts for a family with no insurance. Carol continues to meddle in Meg's life, having her arrested so that she can be detoxed. Cleo is blamed for an explosion in the suture room but it may actually be Dr. Dave's fault.

A recommendation from Weaver allows Jeanie to have temporary approval as a foster parent for baby Carlos. Reggie and Jeanie get married. Lucy and Kovac talk with a young woman whose husband they believe is very dangerous.

Weaver tries to save the life of a rape victim while Corday struggles with feelings of disdain as she is forced to save the rapist. Cleo treats a teenage alcoholic boy whose alcoholic mother refuses to recognize her problem or his.

Kovac and Haleh take care of Hathaway's twins so the new mother can finally get some rest. The job transfer for Carla's husband does not get approved allowing Reese to stay in Chicago. Lucy endeavors to get a heart transplant for a young woman and goes to Romano's house begging him to perform the surgery.

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.

Two boys brought in after a fight at school leads Cleo to discover that one of them has been injecting himself with hormones. Hathaway's obstetrics nurse, Abby Lockhart, joins the ER as a third year medical student on an ER rotation.

Carter seeks psychiatric help because he can't sleep. He then visits the wife of his attacker. Weaver returns to work after her suspension. Hathaway and Kovac share a kiss.

When Anspaugh decides to retire as chief of staff and return to surgery, he appoints Romano as his replacement. Greene expresses reservations about the decision, but Weaver does not support Greene. Romano makes Weaver the new chief of emergency medicine.

After his mother's funeral, Dr. Greene comforts his father in San Diego. In Chicago, Romano surprises Corday by appointing her associate chief of surgery. Corday treats Elaine, Carter's lover, for breast cancer.

A prank in a high school science class goes terribly awry, injuring a teacher and several students. Hathaway discovers Meg's drug addiction. Weaver and Greene notice Lawrence gets easily confused.

Kovac witnesses an accident and saves the young victim's life. Carter slowly recovers from his brutal attack and undergoes excruciating physical therapy. Hathaway helps two sexually active 14-year-old girls.

In order to get her paitient to tell her the location of a missing body, Corday agrees to grant him a fatal wish. Kovac befriends two brothers. He tells Weaver that his wife and children died in the Bosnian war. Former medical student Deb Chen returns to County General as a resident, using her Chinese name, Jing-Mei Chen.

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.

Hathaway befriends an out-of-work waitress, Meg. Seven-months pregnant, Meg cannot afford prenatal care. Hathaway invites her to the hospital, performs free tests and helps her interview for a job in the cafeteria.

Chen's patient refuses to reveal to his daughter that she might have inherited a terrible disease from him. Weaver defies Romano's authority and performs a procedure that gets her suspended. An available kidney causes friction between Corday and Kovac as they decide which one of their patients will get it.

After Corday refuses to perform exploratory surgery on Cleo's patient, Cleo enlists Benton's help, infuriating Corday. Abby cares for a pregnant woman with five children who wants an abortion. Greene lovingly tends to his dying father at home.