Dr. Lewis tries to get a mentally disturbed individual admitted to the psych ward. Carter has a difficult day, treating many members of wedding party, suffering from food poisoning. Dr. Ross finally visits Carol, eight weeks after her suicide attempt. Dr. Greene deals with an elderly gentleman having a difficult time letting go of his dying wife. He also discovers that Jenn passed the bar exam.

A business contractor with a bad heart gathers his family around him in the ER as he prepares for the end. Dr. Ross helps an asthmatic teenage girl when her mother doesn't have the funds. Carter worries that he may have contracted an STD from Liz. Dr. Lewis treats a teenager with alcohol poisoning. Jenn Greene prepares to move to Milwaukee.

The air conditioning quits on the hottest day in October which, coupled with closed ERs in Chicago's other two hospitals, leads to an extremely hectic day. Dr. Ross treats a six-year-old suffering from a cocaine overdose; Ivan Gregor, the liquor store owner, shoots and seriously wounds a young teenager. Susan's immature sister Chloe drops by, wreaking havoc in Susan's life. Doug picks up a pharmaceutical saleswoman, much to Carol's displeasure.

Benton and Langworthy interview for the Starzl fellowship. A drunk Chloe throws a tantrum in the hospital. Benton saves a man with a throat wound, earning Morganstern's praise. Carter has a good day, winning a bottle of champagne and getting three leads on apartments. Carol has second thoughts about moving in with Tag after a spontaneous kiss with Doug.

Carter and Benton treat a suicidal transgender woman. Doug feels like a 'kept man' in his relationship with Linda Farrell. A patient entrusts Carol with the particulars in an accident. Cvetic continues to battle his demons, ending up wandering down the middle of a crowded street.

A severe blizzard leaves the ER utterly devoid of patients, leaving the staff free to goof off. In the middle of their fun, a call comes from dispatch, informing the ER of a 40-car pile-up with dozens of casualties. The ER goes from being deserted to capacity. All surgeons are called in. Bob surprises everyone with a quick and life-saving decision. A new doctor, Angela Hicks, arrives just at the right time. Ross and Linda return from the Caribbean just as Carol makes a surprise announcement.

Benton makes a critical error when he publicizes the availability of a dying man's organs before obtaining the wife's permission. Lewis discovers that Cvetic has quit his job at the hospital, moved out of his apartment, and dropped out of sight. Carter makes a move on Susan. Chloe announces her pregnancy.

Carter fumbles his way through his first look at surgery. Dr. Lewis' nemesis, Dr. Kayson, makes her New Year's Day decidedly unpleasant. Chloe announces she's moving to Texas with her boyfriend.

Deb and Carter compete furiously for procedures after Benton announces their books are due a week earlier than previously announced. Deb commits a nearly deadly error on a patient while trying to keep up with Carter. Doug's relationship with Diane Leeds grows. Peter and Jackie decide to put their mother in a home. Dr. Greene is put on trial, so to speak, in the M conference for Jodi O'Brien. Chloe returns.

Susan has her hands full with a pregnant Chloe. Benton goes to dinner with Jeanie. Greene further alienates Swift when he decides to honor a family commitment rather than stay longer at the ER to help him. Carter makes a good impression on Dr. Swift. Doug turns down an offer to "celebrate" with Linda Farrell, instead getting more serious with Diane as he agrees to coach Jake's Little League team.

Mark and Jennifer struggle to remain together as Mark has moved in with her in Milwaukee. Doug coaches Jake's little league team. Chloe's irresponsibility wears Susan down. Carter asks Benton to fill out a recommendation for the ER sub-I. Carol and Tag try to write their wedding vows; he becomes upset when Carol invites Diane Leeds, knowing that she'll bring Doug. Peter exhibits a growing attraction for Jeanie. Susan discovers what happened to Div when she spies his picture in a cabbie's dating service photo book. The staff discovers that Carter comes from a wealthy background.

Susan is forced into the role of parent when Chloe gives birth and both Chloe and her mother, Cookie, shirk responsibility. Doug is surprised and a bit frightened when Diane suggests they move in together. Unfortunately, Linda Farrell happens to be around to take advantage of his nervousness. Carter is offered the ER sub-I but turns it down in anticipation of receiving a surgical position. Peter receives unpleasant news; his mother has died.

Carter faces his last day in the hospital with aplomb, harshly grading Benton on an evaluation report. He later rescinds the report after finding out that the surgical sub-I is his. Carol faces wedding day jitters, culminating in Tag's deciding to call off the wedding. Chloe disappears again, abandoning little Susie with Susan. Dr. Swift changes his mind and decides to support Mark. Jake visits Doug.

The ER treats victims of a gang shootout. Carter arrives late and unprepared for his new position. Mark learns all about being an attending, including senior staff's habit of bad-mouthing the residents, particularly Doug Ross. Mark hires a new chief resident, Kerry Weaver. New third year med students arrive to complete their ER rotation.

Kerry Weaver manages to offend just about everyone in her first day as chief resident. Carol goes on a ride-along with paramedics Shep and Raul, sharing a ferris wheel ride with Shep. Peter and Jeanie's secret relationship comes to a head. Susan is stuck caring for Little Susie while Chloe attends school. Dr. Ross has his hands full with a young pyromaniac. Carter shows interest in med student Harper Tracy.

Carter gets his first patient...and loses him. Susan's feud with Kerry Weaver intensifies when Weaver demands all of Susan's procedures be cleared with her. Chloe abandons Little Susie again for a lucrative career in the flea market business. Carol finishes her paramedic recertification by picking up a very overweight, lethargic man. Shep hits on Carol. Jeanie ends her relationship with Benton. Wendy conducts interviews with various ER staffers for an article on Dr. Greene. Dr. Ross cares for a four-year-old Asian boy with AIDS.

Shep and Raul respond to a massive fire without proper equipment, risking their lives to save addicts and their children. Shep will be okay, but Raul has third-degree burns covering his body; it's only a matter of time. The ER is flooded with burn victims. Chloe returns to Chicago. Doug is stood up by his father for a basketball game.

Susan institutes extra precautions in case Chloe tries to reclaim Little Susie. Mark changes his look, growing a goatee and wearing contact lenses. Carol and Jeanie square off over the care of a transient. Carter celebrates when he receives his residency match, putting his patient and his job at risk. Shep, still suffering from Raul's death, is surly with new parter Reilly. Benton and Ross have differences when Peter discloses a critical mistake made by Doug, raising animosity between the two.

Mark finds himself manning a very crowded ER on his scheduled night off, filling in while Doug is out with whiplash and Susan meets with her lawyer. He tries to juggle hunger pangs, 40+ patients in the waiting room and a never-ending stream of traumas.

Carter engages in competition with new surgical resident-in-training Dale Edson upon learning that residents will be evaluated and graded; only the top ones advancing to second year. It doesn't help that Dale once had a relationship with Harper. Mark flirts with infomercial director Iris. Peter faces the fallout from his altercation with Doug when surgeons begin dropping him from procedures. Shep begins exhibiting uncontrolled hostility, first to a patient being abusive with Carol, then a pedestrian. Susan and Chloe try to reach an agreement regarding Little Susie.

Susan throws herself into her work to escape her stressful personal life, earning recognition from Kerry and Mark, who begins preliminary discussions on next year's chief resident. Carter needs a pedes rotation, and fast, with Doug to graduate med school. Doug takes up with his father's girlfriend. Shep overreacts and attacks an Asian boy interfering at a scene. Mark and Jenn try to discuss their divorce amicably, with unforeseen results. Benton is named Resident of the Year. Harper leaves for an OB rotation at Parkland in Dallas.

When Dr. Lewis gets a hysterical call from her niece, Susie, she hurries to New York to search for the child and her sister Chloe.

The crossover continues on Third Watch S03E19 Unleashed