The new residents at Angels Memorial Hospital in Los Angeles are introduced to the ER and deal with a series of patients including a dropped-off gang member, a foreign child with a collapsed lung, an organ donor and his daughter who were in a car crash, a stroke patient, and a nine-month pregnant woman with unexplained flu symptoms.
The ER deals with car crash victims, a hockey player suffering from seizures who is unwilling to acknowledge his illness, a blind 14-year-old climber and a woman desperate to have her dead husband's baby.
The ER is under a 36 hour period of code black and receives two brothers involved in a car accident. Their mother shuns one son because she holds him responsible for the death of the other. Leighton is pushed by fellow resident Savetti to cut open the chest of a patient who had come in with pelvic, chest and rib fractures. Lorenson faces a moral dilemma while treating a prisoner with kidney failure.
A new surgical attending Cole Guthrie joins Angels Memorial with the help of his estranged father and clashes with Leanne over their contrasting approaches to medicine. Christa has a crisis of confidence in the middle of a procedure on her first infant since the loss of her son.
The ER is overwhelmed with patients with an unknown respiratory ailment, requiring them to be quarantined. When Dr. Hudson's mother is among them, he clashes with his father over the proper treatment. A man impaled on a piece of rebar is desperate to make up with his daughter.
Leanne must deal with the difficult decision of whether to save Tom Moreno (Michael Trucco), the police officer who helped her during her family's accident, or his shooter, who has more serious injuries. Also, when Malaya's pregnant ex-girlfriend, Carla Niven (Shiri Appleby), arrives at the hospital with pain in her arm, Malaya is shocked by her MRI results.
The ER must deal with the injured after a car ran onto a sidewalk at a street fair, along with the driver who seems to suffer from seizure-induced amnesia. Other patients include a child of an illegal immigrant, a young woman whose eye is bulging out (Skyler Day), an old lady prepared to face her end, and a man with an enlarged organ who puts Savetti in an uncomfortable position.
On a rainy LA night, the ER deals with the victims of a boating accident, an HIV-positive patient which endangers Savetti and causes tensions between him and Leighton, and Guthrie and Rorish butt heads on a surgery. Pineda runs a bone marrow drive for her former lover, much to her dismay.
A family is the victim of a home invasion with a father who was stabbed near the heart, a mother who was repeatedly stabbed, and a son who was injured during his search for rescue by jumping from a window of the building. Mario and Angus clash over the mother who has bruising around her eyes. Taylor is suspended for bringing a child around the ER, and the doctors clash early with his replacement. Meanwhile, a son struggles to get his father off life support.
The ER adjusts to the new department head who questions Rorish's decisions. An ambulance arrives with its paramedics knocked out by their patient, who attacks Jesse. Later, Jesse has a heart attack. As the doctors try to save him, other patients include a man hit by a train, the daughter of a controlling Beverly Hills mother, and the wife of a veteran who is struggling with addiction. Meanwhile, Mario leaves the hospital to find the train victim's son who has intellectual disabilities, against H
Leanne, Neal, Christa, Angus, Mario, Malaya, and Heather are sent to the scene of a multi-car collision on a canyon road above Los Angeles. Leanne clashes with the physician in charge, making a decision he questions. Christa treats an injured family whose car is in a ravine. Angus, Heather, and Mario help a man stuck in cement. Mario and Heather find their lives in danger when a patient's husband holds them at gunpoint to save his wife. Meanwhile, Jesse recovers from his heart attack.
Neal stays behind at the car crash scene to look for Christa, Mario, and Heather. Mario and Heather continue trying to revive the wife of a grieving husband, who later attempts to commit suicide. Leanne and Neal face the consequences of having left a patient in Malaya's care resulting in both doctors being investigated. After Heather hugs Angus, he decides he wants to ask her out, unaware she has a relationship with Mario. Carla gives birth to her son, Philip, before dying.
When a 16-year-old girl who is from a Christian-Scientist family comes into Angels requiring surgery, the ER must deal with her father who forbids the surgery. Angus' brother begins an observational rotation prior to accepting a new job in the hospital as an attending surgeon. Christa treats a patient who is experiencing breathing problems who doesn't seem to be improving; when the patient dies following discharge, she blames herself for her death. Later, Neal and Christa kiss, while Malaya trea
In a shooting accident between two feuding families, one of the victims requires a liver transplant with their cousin being the perfect match; however, the father refuses. Neal and Christa begin their relationship and Leanne forgives the drunk driver who killed her family. Malaya again deals with Gordon, who seems to be following her more often now. Later, he sneaks into the staff lockers to confront Gina, but he stabs her to death. Christa discovers her body and calls for help.
In the aftermath of Gina's death, the doctors are questioned. Gordon had been at the hospital at least 17 times under different aliases and frequently asking for Malaya. Once Gina had been attacked, he followed Malaya to the elevator. She lies to him and takes another floor, but he continues to follow her. He asks her out, but she tells him that she is gay. Angry, he attacks her by slitting her and attempts to rape her. Angus arrives in time and pushes Gordon to the ground. He tells her to go to
Christa becomes insecure in her new relationship with Neal when his ex-girlfriend Dr. Grace Adams (Meagan Good), returns to Angels Memorial after spending a year volunteering in Haiti. Also, New York Giants wide receiver Odell Beckham Jr. comes to the ER to convince his stubborn high school football coach, Pete Delaney (Beau Bridges), to have life-saving surgery. Neal accepts a job as surgical attending at Angels. Christa and Malaya treat a marathon runner and new single mother, Katie Miller (An
Christa and Grace deal with a teenager who claims to have been abused at a camp. Angus begins to take ADHD medication to remain focused, after it is revealed that he deliberately refused to aid Gordon after he removed the knife from his throat, causing Gordon's death. Leanne deals with a VIP patient who had embryos implanted in her without her husband's knowledge. Meanwhile, Christa feels at odds with Grace due to her past history with Neal.
When the location of a presidential debate suffers an explosion, the ER must work under the scrutiny of the Secret Service to save both candidates and their families. Mario confronts Angus about his drug abuse, which in turn leads to Heather being caught by Campbell using his scripts to prescribe the Adderall. The love triangle between Neal, Christa, and Grace becomes more complex. Dr. Rorish asks Dr. Taylor for advice on how to cope with Jesse and the other nurses' impending strike over wages a