The pilot for the popular TV series is set during 24 frantic hours in the lives of a group of doctors, nurses, and staff members of a busy emergency room at a Chicago hospital. They deal with the seemingly endless casualties that stumble into their place of employment. The central characters are the chief resident and family man Dr. Mark Greene, who is considering a job in private practice due to pressure from his demanding law student wife Jennifer; outgoing Dr. Doug Ross, who deals with cases in his own personal way; straight-arrow Dr. Susan Lewis, trying to get by another long 36-hour shift; inexperienced third-year med student John Carter; cocky surgical resident Dr. Peter Benton; and troubled chief nurse Carol Hathaway.

Carol Hathaway returns to work after her suicide attempt. Doug Ross still feels guilty about what happened. An ER patient found walking the streets takes to singing, constantly. Susan Lewis has a run-in with the cardiologist on duty, Dr. Kayson, when he disagrees with her treatment of a heart attack victim. At a case review session, she gets very little support from her colleagues. She also treats a woman who is dying of leukemia and who has good advice for Hathaway. Greene treats a woman who has obviously been beaten by her husband but can't get to agree to get help.

Drs. Benton and Langworthy are unsuccessful in reviving a teen-aged boy involved in a traffic accident and it's left to Carter to determine the boy's identity and notify the parents. Unfortunately, he tells the wrong parents that their son is dead. Doug Ross tells a young patient that he will not be separated from his schizophrenic mother knowing that she will likely be hospitalized for a long time. Susan Lewis tells Mark that she is dating the psychiatric attending physician Div Cvetic. She also treats a salesman whose cell phone is having an odd effect on hospital equipment. Benton forgets that he was supposed to sit with his mother while his sister and brother-in-law were to go out for their tenth anniversary dinner.

Doug Ross' hopes of renewing his relationship with Carol Hathaway take a positive turn after the two of them kiss following a particularly stressful trauma, but his hopes are dashed when she decides to move in with boyfriend Tag. John Carter has a particularly good day when Dr. Green successfully walks him through a complex procedure. Haleh takes Dr. Benton to task when he refuses to act as a role model for a young gangbanger she has an interest in. Benton is also competing with Dr. Langworthy for a prestigious fellowship. It's Susan Lewis' birthday and her sister Chloe shows up at the ER drunk.

The ER staff's slow snow day becomes chaotically hectic when the casualties of a 40 car traffic accident flood in.

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.

Benton is called out of surgery to find his senile mother.

Dr. Kayson becomes Lewis' patient.

Dr. Greene gets offered a new job by Morgenstern.

Carol Hathaway goes ahead with her plans to adopt Tatiana, but her past history makes her ineligible. Benton continues to trade shifts so he can spend time with his mother but it all catches up with him and he has a run-in with Dr. Hicks. Doug Ross treats an abused child. Green, Benton and Carter take extraordinary measures to save a man they later learned had signed a DNR. A consultant arrives to study procedures in the ER, but all is not quite what it seems. Mark Green's wife Jen has an important announcement. Benton's mother has a serious accident when he falls asleep on the couch.

While victims of a gang shootout are being brought in, Carter is late and a new group of third year medical students arrives.

It's Weaver's first day and she doesn't exactly make a lot of friends. Carol rides along with the paramedics.

Doug and Harper had sex. Mark finds out about this. So does Carter.

Doug saves a kid who's stuck in a flooded culvert and becomes a local hero when a TV helicopter films part of the rescue operation.

Doug gets the opportunity to stay at the ER thanks to the publicity surrounding his rescue of a drowning boy the week before.

Jennifer and Rachel have been involved in a car accident and Mark rushes to Milwaukee where they're in the hospital.

Benton has to attend a banquet at Vucelich's home and asks Jeanie to go with him. Mark hesitates to tell Rachel about the divorce.

It's his day off, but Mark shows up for work anyway. After a patient dies and Morgenstern wants to speak to him, Mark soon regrets coming in after all.

Mark has to work for the fourth night in a row while a lot of the staff are absent and the number of patients is towering.

In order to avoid having to deal with her personal problems regarding little Susie, Susan wholly absorbs herself in her work.

Mark Greene strikes a deal with Kerry Weaver - he will support her application for an ER attending position if she in turn will support Susan Lewis for Chief Resident. When Susan doesn't get the job, Mark is told to go ask her why. Carter is finally going to graduate and wants Benton to attend the party his family is throwing for him. Unfortunately, Carter decides to sit with a young patient awaiting a liver transplant and misses his own graduation ceremony. With the news she has received about her former husband Al's health, Jeanie Boulet decides to have herself tested. Doug Ross' girlfriend Karen forges his prescription for percodan. Hathaway's boyfriend, Shep, is refusing to undergo his anger management treatment. Mark's ex-wife Jen tells him that she is going to re-marry. Loretta Sweet asks Greene if he would become guardian to her kids.

While the whole staff is worried the ER might close, Jeanie has her own problems in dealing with being HIV-positive.

Encouraged by Carol, Mark finally asks Susan out. Benton tries to save a boy, despite the fact Doug thinks he's brain dead.

Carol worries about her physics exam while Mark is heart-broken about Susan's departure and focuses solely on his job.

Benton can't keep his mind on the job, Mark and Chuny break up and Carol does what she needs to do regarding the fatal error she has made.

While a film crew is filming in the ER, it's Elizabeth Corday's first day.

Carter is excited about getting his own med student, and Mark and Carol interview candidates for the desk clerk position.

Dr. David Morgenstern returns after a six-month absence recovering from his heart attack. His new outlook on life however has Kerry Weaver questioning his abilities. Elizabeth Corday decides to start a study on the use of artificial blood in the ER, but the only problem is that she fails to discuss it first with Rocket Romano. Doug Ross decides to apply for an ER attending position. Scott Anspaugh suffers a major relapse. Anna Del Amico is confronted by an irate husband who wants his ill wife to terminate her pregnancy. At the free clinic, Carol Hathaway has to deal with the case of an underage high school student who is sleeping with her 40-year-old teacher. Peter Benton hits a pedestrian with a car but Carter helps him out with an important piece of information.

When a compatible bone marrow donor cannot be located, Scott Anspaugh agrees to undergo a new round of chemotherapy, even though there appears to be little point. Doug Ross suggests to Jeanie Boulet that Scott may have agreed to the therapy because of her. Mark Greene has taken on the task of organizing the annual ER banquet only to find that Jerry, on whom he had been relying for much of the preparation, hasn't quite delivered. John Carter confronts his grandmother when he learns that she has cut off funding for Carol Hathaway's free clinic. In the OR, Peter Benton has a major confrontation with Dr. Morgenstern, pushing him aside and taking over an operation. Greene and Weaver criticize Doug Ross over his handling of a sick child and her mother.

Following the incident in the OR, Dr. Morgenstern and Dr. Benton present the case to their colleagues. As a result, Peter Benton finds himself suspended for insubordination pending a full inquiry. Jeanie attends Scott Anspaugh's funeral and has some information to share with the boy's father. Anna Del Amico finds herself ethically unable to perform an abortion and is taken to task by Dr. Weaver. John Carter gets the hospital to take legal guardianship of a patient he feels has been subjected to elder abuse, but subsequently doubts that he made the right decision.

An elderly man is brought into the ER after being mugged, and sees things as if it were the 1960s.

An elderly man is brought into the ER after being mugged, and sees things as if it were the 1960s.

Following the incident in the OR, Dr. Morgenstern and Dr. Benton present the case to their colleagues. As a result, Peter Benton finds himself suspended for insubordination pending a full inquiry. Jeanie attends Scott Anspaugh's funeral and has some information to share with the boy's father. Anna Del Amico finds herself ethically unable to perform an abortion and is taken to task by Dr. Weaver. John Carter gets the hospital to take legal guardianship of a patient he feels has been subjected to elder abuse, but subsequently doubts that he made the right decision.

Benton has to attend a banquet at Vucelich's home and asks Jeanie to go with him. Mark hesitates to tell Rachel about the divorce.

Dr. David Morgenstern returns after a six-month absence recovering from his heart attack. His new outlook on life however has Kerry Weaver questioning his abilities. Elizabeth Corday decides to start a study on the use of artificial blood in the ER, but the only problem is that she fails to discuss it first with Rocket Romano. Doug Ross decides to apply for an ER attending position. Scott Anspaugh suffers a major relapse. Anna Del Amico is confronted by an irate husband who wants his ill wife to terminate her pregnancy. At the free clinic, Carol Hathaway has to deal with the case of an underage high school student who is sleeping with her 40-year-old teacher. Peter Benton hits a pedestrian with a car but Carter helps him out with an important piece of information.

When a compatible bone marrow donor cannot be located, Scott Anspaugh agrees to undergo a new round of chemotherapy, even though there appears to be little point. Doug Ross suggests to Jeanie Boulet that Scott may have agreed to the therapy because of her. Mark Greene has taken on the task of organizing the annual ER banquet only to find that Jerry, on whom he had been relying for much of the preparation, hasn't quite delivered. John Carter confronts his grandmother when he learns that she has cut off funding for Carol Hathaway's free clinic. In the OR, Peter Benton has a major confrontation with Dr. Morgenstern, pushing him aside and taking over an operation. Greene and Weaver criticize Doug Ross over his handling of a sick child and her mother.

While a film crew is filming in the ER, it's Elizabeth Corday's first day.

Encouraged by Carol, Mark finally asks Susan out. Benton tries to save a boy, despite the fact Doug thinks he's brain dead.