Weaver and Legaspi have spent the night together, although Kerry appears shy of beginning a relationship. She also battles Luka over calling the authorities about an illegal sweatshop employing one of his patients, which causes the owners to torch the place. Greene is back to work, but mixing up his pronouns, referring to a male patient as a "she." Corday freezes again during surgery, but is able to overcome her fears. Romano talks benton into taking a job as County's director of diversity. In the wake of his Vicodin slip, Carter is banned from prescribing drugs. He later visits Chase at his home, and admits his addiction. Abby treats two horny old men.

The episode was rated 7.61 from 104 votes.

Carter meets a new pedes intern, Rena Trujillo. He and Luka are then dispatched to the site of a major train wreck. Carter must perform a tricky double amputation on an injured firefighter after Corday goes into early contractions at the scene. After Elizabeth returns to the hospital, Abby and Chen treat Corday, who is told to stay on bed rest. Benton lets prospective med student William White follow him around the ER. Weaver calls Legaspi for a psych consult on a suicidal girl who caused the train crash by driving her car onto the tracks. Luka wrestles with his faith, revealing that he could have saved his wife by sacrificing his daughter. Bishop Stewart grants him absolution before his death.

The episode was rated 7.61 from 96 votes.

Luka blows Abby off, and an already-stressed Abby has to deal with an unexpected visit from her estranged mother, who isn't taking the meds prescribed for her bipolar disorder. Corday, eager to leave work for a vacation with Greene, makes a poor surgical decision; after she leaves, her patient experiences post-surgical complications. Benton's nephew is shot and dies. Benton hears Malucci refer to his late nephew as a "banger" and Benton beats him. Chen decides to put her baby up for adoption and visits the child's father, nurse Frank Bacon. Luka accuses a pregnant girl's father of beating her.

The episode was rated 7.65 from 98 votes.

Abby is flabbergasted when Maggie reveals her plans to move back to her birthplace of Minneapolis. Abby reveals to her mother that she was pregnant once, but had an abortion, scared about the genetic possibility of herself or her child turning out bipolar. Meanwhile, Carter and Chen are both shot down in their bids for chief resident. Weaver meets Legaspi's new girlfriend. Carla hits on Benton and freaks out at Cleo after she turns her back on Reese for a second and he injures himself. Mark treats a young abused boy with an extremely irate father. Several staff members play softball.

The episode was rated 7.66 from 83 votes.

Bishop Stewart returns, seeking pain medication from Luka, who also has his hands full dealing with the parents of a 16-year-old who does not want another heart transplant. Abby fills in as Carter's date for a Carter family function and sees her ex-husband there. Malucci treats a gay man who wants to contract HIV from his positive partner. Greene continues an abrupt personality change in the wake of his surgery. Weaver calls someone, making an appointment for a competency review for Mark.

The episode was rated 7.69 from 93 votes.

Carter treats a young paraplegic on his first day back at County. Corday and Greene try to work around a surgeon shortage. Benton discovers that Romano has fired him for his actions last week. Weaver offers Abby a position as a full-time ER nurse. Abby later plants an impromptu smooch on Kovac. Various weird patients arrive at the ER following a beam collapse at a sci-fi convention. Dr. Dave goes out of his way to discover who the father of Chen's baby is. A patient with 'spontaneous human combustion' catches fire.

The episode was rated 7.69 from 98 votes.

Abby's mother decides to stay in Chicago, causing Abby even more trouble. When Weaver accepts Dr. Legaspi's dinner invitation, Weaver learns that she has misunderstood Legaspi's intentions. Carter tries to find a drug addict who has left the hospital against medical advice. Chen's mother visits the ER and invites her to dinner, even though she is surprised by Chen's pregnancy, and speechless when Chen tells her that the father is black. Greene discovers that he has a brain tumor. Corday is sued for malpractice by Mr. Patterson, the patient whose surgery she rushed so she could start her vacation, and later discovers that she's pregnant. Carter saves Abby after an explosion in exam room three.

The episode was rated 7.72 from 97 votes.

Abby wakes up with Luka in his hotel room. At a job interview at a department store, her mother causes a disturbance and later flees town. Benton treats Jesse's girlfriend, who talks to the cops about Jesse's killers and later comes to him for help after a hit is put on her. Corday undergoes a grueling deposition for Mr. Patterson's lawsuit and lies to save her ass. Greene discovers that his tumor is inoperable and later has a seizure. He finally decides to tell Corday about his condition.

The episode was rated 7.74 from 93 votes.

The father of the abused boy that Mark treated last week goes on a shooting rampage throughout the city, looking for anyone connected with the placing of his son in a foster care facility. Mark fears for Elizabeth and baby Ella's safety when Corday doesn't answer her pager. Chen moves one step closer to the chief resident position. Romano fires Legaspi. Weaver confronts Romano, and comes out to him, threatening that she will quit if Kim is not rehired. Carla's husband, Roger, accuses Benton of sleeping with Carla. Cleo cuts her hand while treating an HIV-positive patient. Abby is unhappy with Luka when he sends in her med school reapplication without her consent. Carter expresses his feelings to Abby and begins thinking about his future at another hospital. While treating the shooter alone in an elevator, Mark makes a critical decision regarding his care when the man flatlines.

The episode was rated 7.80 from 94 votes.

While giving birth, Chen undergoes second thoughts about giving her baby up for adoption, a decision complicated by the adoptive parents watching her every move. With an enormous lack of sleep, Carter is called back to the hospital to act as Chen's coach, and is later tempted to take Vicodin to stay awake. Finch and Benton encounter trouble trying to keep Kynesha hidden from the gang. Legaspi plants a kiss on Weaver. Greene and Corday spend the day in New York seeking help for his brain tumor.

The episode was rated 7.80 from 91 votes.

Peter and Cleo may be at fault when a police officer shoots and kills an old woman with dementia. Carter misinforms Rena and tells him that he and Abby had a past liaison. April Fool's Day causes the staffers to play pranks on each other; Malucci gets the worsts of them. Corday endures a particularly long surgery just to prove that she still can. Greene treats three young students who have been huffing carpet cleaner. Luka treats another pregnant teenager, who wants the comfort that a child will bring her.

The episode was rated 7.84 from 93 votes.

Domestic troubles cause problems for Greene and Corday. Later in the day, however, Mark shows Elizabeth their spacious new digs and proposes to her. Chen tells Weaver about her pregnancy; she is 22 weeks along. Carter sees Abby at an AA meeting and she tells him she was an alcoholic 5 years ago, later John asks her to be his sponsor. He also meets with Greene and Weaver about coming back to work. Abby, down from OB, helps a young couple whose baby was born much too early. Benton and Romano clash over an obnoxious homeless man who once again requires extensive treatment resulting from his chronic disdain for maintaining his dialysis appointments. Weaver and Kovac are helpless to assist a severely comatose woman whose longtime life partner is not legally empowered to make decisions on her care.

The episode was rated 7.85 from 98 votes.

After Abby leaves the room for a second, an infant disappears from the hospital. After spending the night at her place, Carter is shocked to find out that Rena is a 19-year-old undergraduate. Greene gets his competency results. Malucci and Mark treat a young boy injecting steroids who is frightened of his father. Legaspi has been accused of sexual misconduct by the teenager who caused the train crash. Weaver is more concerned with hiding their relationship, so Kim dumps her.

The episode was rated 7.86 from 92 votes.

On New Year's Eve, A father injured in an auto accident is unworried about his own health, only his son's. Greene undergoes experimental brain surgery in New York with Corday by his side.

The episode was rated 7.88 from 96 votes.

Benton drops Carter off at rehab in Atlanta. Three months later, a custodial strike is making life difficult in the ER. Chen discovers she is pregnant. Carter prepares to leave rehab. Benton interviews with Romano for a surgical attending position; he later gets it. Carter makes a slow journey back to Chicago, and gets busted for smoking in the aircraft lavoratory. Due to her ex-husband failing to pay her tuition, Abby cannot continue med school until the beginning of the next quarter and confronts her ex-husband at the driving range making a big scene. The ER is swamped with participants from a riot at a high school football game. Carter arrives at the ER and leaves promptly.

The episode was rated 7.92 from 103 votes.