Season Finale: Mario decides to confront Angus; Christa is faced with a surprise; Dr. Mark Taylor returns to help Leanne find money in the budget for the nurses.

Christa must ignore her personal feelings as she and Grace treat a patient who says he was abused at a camp for troubled teenagers; Campbell surprises Grace by asking her out on a date.

Christa becomes insecure in her new relationship with Neal when his ex-girlfriend, Dr. Grace Adams, returns to Angels Memorial after spending a year volunteering in Haiti. Also, New York Giants Pro Bowl wide receiver Odell Beckham Jr. comes to the ER to convince his stubborn high school football coach, Pete Delaney, to have life-saving surgery.

The doctors are questioned following a violent incident inside the hospital that leaves two doctors gravely injured. Also, Neal and Christa make their relationship to the next level after officially disclosing their romantic relationship to HR.

Leanne visits a prison to finally confront the drunk driver who killed her family. Meanwhile, Malaya begins to feel uncomfortable around her patient.

Angus' older brother, an "all-star" ER doctor, tries to secure a position at Angels Memorial. Meanwhile, Christa's romantic feelings towards Neal begin to grow; and Malaya deals with a patient who is obsessed with her.

As the doctors treat patients from the chaotic multi-vehicle accident, a love triangle begins to build between Mario, Angus and Heather. Also, when Malaya learns that Carla is at the hospital, she goes against Carla's wishes and stays by her side during the delivery of her baby.

The doctors find their own lives in danger when they arrive at the scene of a massive multi-vehicle accident on a highway covered in thick fog. Also, Jesse's confidence is shaken following his heart attack, while Carla's condition becomes critical.

Leanne is rattled at the thought of losing Jesse as he fights for his life after suffering a massive heart attack. Also, Mario asks the residents to cover for him when he searches the city for a patient's son, disobeying Neal's direct order not to leave the hospital.

When the lead actor of the musical "The Lion King" tour arrives at Angels Memorial with a throat infection, Leanne gives him a diagnosis that puts both his career and life in jeopardy. Also, the doctors and the cast of "The Lion King" help a 17-year-old boy deal with the difficult decision of taking his father off life support,

Christa experiences her busiest shift yet when she is responsible for all emergencies at Angels Memorial that occur outside of the E.R. Meanwhile, Mario bonds with an older patient with HIV; Malaya starts a bone marrow drive for Carla; and Leanne refuses a date with Cole.

Angus uses his background in psychology to help a woman who doesn't remember how she injured herself and others. Also, when Christa bonds with an illegal immigrant whose son is diagnosed with cystic fibrosis, she becomes determined to help the woman find long-term care for her son in the U.S.

Leanne struggles with whether to treat a police officer who helped her during an accident or his shooter, who has more serious injuries. Meanwhile, Malaya's pregnant ex-girlfriend arrives at the hospital with pain in her arm, and Malaya is shocked by her MRI results.

Neal clashes with his neurosurgeon father over how to treat his gravely ill mother, whose mysterious symptoms force Angels Memorial to quarantine Trauma One.

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. Also, Christa has a crisis of confidence in the middle of a procedure on her first infant since the loss of her son.

The distraught mother of two sons who are in a devastating car accident. Also, Mario bullies Angus into performing an unnecessary operation but lets Angus take the blame when Leanne finds out.

After Christa saves a woman's life, she pleads with Neal to perform a surgery that will ensure the patient's reproductive future. Also, Mario gets into a fight with a patient after he delivers a diagnosis that could imperil the man's hockey career.

Dr. Leanne Rorish puts her new first-year residents right to work at Angels Memorial Hospital, Home to the nation's busiest ER.