Susan Lewis has a run-in with Dr. Jack Kayson, the cardiology attending, when he accuses her of not providing him with all necessary information on a patient who subsequently died. He makes it very clear that Susan will bear all responsibility for his death. Her sister Chloe informs her that she and her boyfriend are moving to Texas. John Carter is still frustrated by Peter Benton's apparent lack of interest in teaching him anything but a new go for it attitude leads to an invitation to assist in a surgical procedure. Benton's sister suggests to him that the time has come for them to put their mother in a care home.

Dr. Kayson becomes Lewis' patient.

It's a day of birthdays. Peter Benton's mother is celebrating a birthday and he tries desperately to find someone to cover his shift. He makes a choice however when Dr. Hicks suggests that he's been absent too often and may wish to consider a leave of absence until his mother's situation is resolved. Carter thinks it's Benton birthday and has a surprise for him. Mark Greene's daughter is also having a birthday but he misses that due to an emergency at the hospital. An elderly, solitary man in the final stages of cancer arrives in the ER on his birthday. Carol Hathaway suggests to her fiancé that they adopt little Tatiana, the AIDS patient abandoned in the ER. Ross has to deal with a young child who was kicked out of a window.

Dr. Benton has to deal with the aftermath of his mother's fall and crosses the line with the surgical attending when he insists on scrubbing in for her operation. Dr. Greene deals with Jodi O'Brien who is two weeks away from giving birth. With the obstetrics attending unavailable, he decides to try to deliver her baby in the ER, with tragic results.

Dr. Greene is still having trouble dealing with cases in the ER and the new Chief of the ER is growing increasingly concerned. Greene also faces a difficult peer review to examine his handling of the Jodi O'Brien case. Dr. Benton takes on the difficult task of telling his mother that she must be placed in a home with full-time care. Susan's very pregnant sister Chloe returns to live with her. Dr. Ross deals with the case of a young girl with a heart condition while Ross and Carter encounter a patient who refuses treatment for tuberculosis. When Benton asks Deb Chen and Carter to submit their procedures book in a few days, Deb feels she has to get a few more procedures under her belt if she's to best her fellow student. Unfortunately, her eagerness leads to near tragedy for a patient.

On a fateful Mother's Day, several staffers in the ER face possible life-changing events. Susan Lewis' sister Chloe gives birth to a beautiful - and healthy - baby girl. Things start to go wrong however when their mother Cookie - who had agreed to take in Chloe and the baby - suddenly decides she's done enough and Susan will have to take care of it. Carter turns down an offer for an ER sub-internship in the hopes that he'll get an offer in surgery. Dr. Hicks has news for him however. Benton's mother takes a turn for the worse. Carol Hathaway is overwhelmed with the final preparations as her wedding day approaches.

The feud between Susan and Weaver gets to the point where Mark has to step in.

It's the first day of Carter's internship. He has a 36 hour shift and overnight he has to cover the ER, the ICU as well as the surgical patients.

Doug treats a dying 17-year old cystic fibrosis patient who doesn't want to be resuscitated. Carter gets to operate on Benton.

Benton takes a day off to help Carla. Carter finds out Edson falsified a chart.

Anspaugh is furious when Carter tells him he wants to quit surgery. Charlie is brought in with an overdose. Mark keeps struggling with his beating.

Mark finds out Cynthia has moved. Carter's cousin Chase is brought in because of a heroin overdose. Doug and Kerry clash after she found a flaw in his study.

Benton and Elizabeth Corday spend the night together. Corday is shocked when Robert Romano suggests that they go out on a date. John Carter and his grandmother clash over the future of Chase Carter; she wants him cared for at home while John feels he should remain institutionalized where he can continue to receive therapy. Carol Hathaway finally gets around to inviting her mother to a Sunday brunch with her and Doug but is a bit surprised when she shows up with her boyfriend. In the ER, Hathaway comforts a man who is going to die from chemical burns.

Carter and Weaver become unlikely roommates. Lucy is having problems with Carter, and Greene picks up on their squabbling. Corday works long shifts which leads to her exhaustion and a critical medical error, causing a rift with Dr. Anspaugh and problems for Benton. Greene has unpleasant flashbacks when he's hazed by the well-meaning paramedics. Jeanie worries when she and Doug treat a young boy whose childlike mother clearly depends on his 6-year sister to make all decisions. Kerry rediscovers her joy of practicing medicine and decides not to pursue the open ER Chief job, which goes instead to a Dr. Amanda Lee.

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.

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.

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.

Dr. Carter is allowed a cautious restart with small steps. An extremely blond Dr. Malucci is very curious who's made Dr. Chen pregnant. Dr. Benton has been written out of all the hospital's systems and is stunned by Dr. Romano. An unfortunate incident at a Science Fiction convention makes it look like scenes from the movie 'Mars Attacks'.

Benton is unable to find a job after Romano negatively influences local hospitals. He reluctantly agrees to accept Romano's demeaning offer of a per diem job at County with no benefits. Kovac and Abby are attacked by a mugger with a steel pipe. Injured, Kovac protects Abby and smashes the robber's head on the ground repeatedly.

Dr. Corday suggests a quick surgical procedure for a patient with back pain before taking off on a romantic weekend with Dr. Greene. Abby's mother, Maggie, unexpectedly visits the hospital and wreaks havoc on Abby's life. Dr. Chen needs the father of her baby to sign paperwork to go through with the adoption.

Abby's mother decides to stay in town; Carter attempts to find a drug addict who left the hospital: Greene discovers his health is failing.

Weaver returns to the emergency room after a self-imposed sabbatical of three weeks, wondering how her newfound lesbian identity will affect her workplace relationships. Having purposely allowed a mass murderer to die, Greene must keep the secret amidst the scrutiny of his superiors.

Greene's daughter comes to live with him and Corday. Carter and Abby become more intimate. Chen must prove her skills while saving a baby. Weaver terminates Malucci after witnessing him having sex in an ambulance.

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.

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.

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 John's grandmother is unwell. Elizabeth Corday is convinced that other doctors are refusing to work with her as a result of the mysterious deaths. Mark Green thinks she's overreacting but she's determined to find out what happened to her patients. Abby and Luka argue over the attention he is paying to a trainee nurse's aide. Dr. Benton finds himself in court to retain custody of his son, Reese. Carter and Susan Lewis treat a young woman who is both a law and a medical student. Green has to collect his daughter at school when she is suspended.

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. Luka tells Abby that he may marry Nicole, who has told him she is pregnant. Dr. Green lays down the law when the police bring in a high school student and he learns that his daughter is outside sitting in the police car.

Dr. Benton is awarded full custody and Roger receives visitation every other weekend.