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 and a nine-month pregnant woman with unexplained flu symptoms.
2. We Plug Holes
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.
3. Pre-Existing Conditions
During a 36-hour shift, the doctors are faced with a distraught woman whose sons were in a devastating car accident and Mario makes Angus perform an unnecessary operation.
4. Sometimes It's a Zebra
Dr Guthrie's estranged son joins Angels Memorial staff and clashes with Leanne and Christa loses her confidence during a procedure on an infant.
5. Doctors with Borders
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.
6. In Extremis
Leanne is faced with a tough choice when a police officer - with whom she shares a personal connection - and his shooter both need urgent medical care. Meanwhile, Malaya's pregnant ex-girlfriend arrives at the hospital with a pain in her arm.
7. Buen Arbol
Angus utilises his background in psychology when a woman cannot remember how she injured herself and others and Christa bonds with the mother of a patient with cystic fibrosis.
8. You Are the Heart
The ER deals with the victims of a boating accident, an HIV-positive patient endangers Savetti and causes tensions between him and Leighton, and Guthrie and Rorish butt heads on a surgery.
9. The Son Rises
The lead actor of a popular musical receives a diagnosis that threatens his life and career, a 17-year-old boy whose father is on life support faces a difficult decision and Taylor is suspended for bringing a child around the ER.
10. Cardiac Support
The ER adjusts to the new department head who questions Rorish's decisions, Jesse has a heart attack and, as the doctors try to save him, they have to deal with an influx of other patients including a man hit by a train.
11. Black Tag
Heavy fog at the scene of a massive multi-vehicle accident puts the doctors in danger and Leanne clashes with the physician in charge, making a decision he questions. Meanwhile, Jesse recovers from his heart attack but his confidence has taken a hit.
12. The Fog of War
A love triangle starts to form as the doctors continue to treat patients from the multi-vehicle accident, meanwhile Malaya disregards Carla's wishes and stays by her side as she delivers her baby.
13. First Date
A 16-year-old girl from a Christian-Scientist family comes into ER requiring surgery but her father forbids it and Angus's brother begins an observational rotation prior to accepting a new job in the hospital as an attending surgeon. Meanwhile, a patient Malaya is treating becomes obsessed with her.
14. The Fifth Stage
Leanne visits a prison to confront the drunken driver who killed her family and, in a shooting accident between two feuding families, one of the victims is required a kidney transplant with their cousin being the perfect match. Meanwhile, Malaya's stalker sneaks into the staff lockers to confront Gina.
15. Diagnosis of Exclusion
When a violent incident inside the hospital leads to grave injuries, the doctors are questioned as to how events unfolded. Meanwhile, Leanne is given Gina's job and Neal and Christa finally disclose their relationship to human resources.
16. Hail Mary
Christa feels insecure when Neal's ex-girlfriend, Dr Grace Adams, returns to the hospital after a year of volunteering in Haiti. Meanwhile, New York Giants wide receiver Odell Beckham Jr arrives in the ER to convince his stubborn high school football coach, Pete Delaney, to have life-saving surgery.
17. Love Hurts
Christa and Grace deal with a teenager who claims to have been abused at a camp for troubled teenagers but Christa feels at odds with Grace due to her past history with Neal. Meanwhile, Leanne deals with a VIP patient who had embryos implanted in her without her husband's acknowledgement and Angus begins to take ADHD medication to remain focused.
18. Blood Sport
When an explosion occurs at the location of a presidential debate, 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 and the love triangle between Neal, Christa, and Grace becomes more complex.