Head Nurse Jesse Salandar takes the four new residents -- Mario Savetti, Christa Lorenson, Malaya Pineda, and Angus Leighton -- on an orientation tour of the ER. As they meet the head of the residency program, Dr. Leanna Rorish, a gunshot victim is dropped off at the ER entrance. Rorish dumps the new residents into the deep end, having them assist her with the patients care. When Christa points out that by the time a vital arterial repair is completed the patient will have run through more than six units of blood, Rorish decides to use a controversial, experimental procedure to place the patient into suspended animation.
Dr. Neal Hudson voices his concerns about Rorish's reckless behavior to the chief of the ER, Dr. Mark Taylor. Taylor defends her, saying she gets results with patients and with students. Neal hints at some tragedy in Leanne's past that changed the way she practices medicine. Rorish interrupts their conversation, admonishing Neal for correcting her in front of the residents. They disagree about general treatment of patients, and she insists that she is the doctor that patients need when they come to the ER.
As a kid comes in with a broken arm from a skateboarding accident, Rorish walks the new residents through Angel's triage system. The residents get to know each other some -- Malaya did her internship at Angels when Angus' brother was a resident there. The residents are told they'll be assisting other doctors and taking light cases on their own. A stroke patient comes in, and Malaya recognizes that he's a candidate for TPA, sharing that information with Angus. After sharing the answer with Rorish, Angus is assigned to the case, while Malaya is sent off to work on her own. Rorish takes Christa and Mario with her. Malaya doubts her status with Rorish and Jesse reassures her about her abilities.
Neal and Leanne take in a father and daughter who were in an accident together. The girl is panicking and Rorish promises to give her the honest truth as soon as they know what's wrong with him. Rorish quizes the residents on the father's status; Mario gives a cursory answer, but Christa recognizes that he is brain dead. Neal is treating the daughter, Ariel, who refuses to call her aunt until she knows her dad is okay.
The stroke patient is exhibiting expressive aphasia, indicating a left hemisphere clot. Since the incident is inside of the window, the doctors want to administer TPA, a clot busting drug, but need to make sure that the blockage hasn't started bleeding into the brain tissue. Angus is sent back to the nurses station, where he is assigned to skateboarding kid. He's told to xray the kid's arm and set it in a cast.
Rorish updates Neal on the father's status, and that he's an organ donor. They need to tell Ariel as soon as possible so that they organ recovery can go ahead. They decide to tell her together. Rorish struggles with the explanation, and Neal comes through, comforting the girl.
Jess tells Rorish the donor team is arriving as she watches Ariel and Neal with the girls father. The stroke patient is a candiate for TPA, and Dr. Guthrie explains the risks. Christa is sent to assess a pregnant woman who is suspected of having the flu. Mario goes with her, questioning how she knows so much and her age. He suspects she's on her second residency, but she explains that she was a wife and mom. The patient complains of a headache, and Mario suspects she's using heroin based on old tract marks. He concludes she's in withdrawal, but Christa suspects it's something else. Rorish orders them to call a social worker and release her. Christa wants to order a tox screen regardless.
Jesse has Malaya take over for Angus with the skateboarder while he goes to administer the TPA. She questions the state of the kid, but Angus says he's jus sleeping off a high. Angus and Guthrie administer the TPA, and it's successful.
The skateboarder leaves his chair as a ten year old is brought in with breathing trouble. Rorish diagnoses the child with a collapsed lung based on his ethnicity. The ER is at code red, and at the next bed, Hudson is treating a patient in the next bed. Rorish plans to treat Basti with a chest tube, allowing Angus to take over the procedure. Neal wants Leanne to go and talk to Ariel, who has been asking for her. The skateboarder wanders into the trauma room and collapses from an undiagnosed head injury. The ER elevates to code black.
Rorish tries to arrange a neurosurgeon to come to the ER for the skateboarder, but no ne is available. She takes the kid to CT, leaving Angus to manage the chest tube. The procedure doesn't immediately work, and Angus panics. Malaya talks him through what needs to be done, and the kid recovers. Angus leaves and Malaya closes.
Leanne fires Christa for going against her instructions and ordering a tox screen. She continues to argue with neuro about sending down a surgeon. Christa sees Mario on the way out, and realizes that the patient was likely suffering from carbon monoxide poisoning. She calls the patient at home, but there is no response -- the woman is passed out on her floor.
A man is brought in with a crushed femur, and Neal takes him to the trauma room where Leann is preparing to drill burr holes in the skateboarder. Taylor arrives with a call for Rorish -- Christa is stuck in an ambulance on the 101 with the pregnant patient. There isn't time to get her to the hospital and get her in the hyperbaric chamber, so Christa will have to perform an emergency C-section. Neal and Leanne talk her through the procedure while simultaneously taking care of their own complicated procedures. In the end, the man's leg is saved, the boys brain pressure is relieved, and Christa delivers a baby girl.
Angus and Malaya visit an old operating theatre and discuss their insecurities. Malaya assures Angus that he just needs confidence, and he reveals that he only got into the program because his father is on the hospital board. Guthrie finds them both and reassures them both about their first day.
Rorish updates Christa on the mother's status, and asks why she is in the program. Christa reveals that her son died from a glioblastoma, and she picked up so much medical knowledge caring for him that she thought she should make it official. Christa recognizes Leanne as another survivor of tragedy, and Leanne reveals that she lost everyone.
The next day, Leanne greets Ariel in the lobby and takes her up to a ward. She introduces her to a young girl -- the recipient of the father's heart -- and Ariel listens to the girls chest. Leanne returns to the ER, where the victims of an apartment fire are beginning to arrive.