A drug bust-turned-shootout tests the bravery of all doctors as they race to save a girl in the crossfire. Willis shifts his career focus to field medicine. Leanne faces the new but tragically familiar challenges that parenting presents.
Jesse is in denial when his brother arrives at Angels Memorial in bad shape after being pinned in a warehouse collapse and further tests reveal he has advanced congestive heart failure. Also, Willis opens up to Rox about his brother who was killed in Afghanistan.
Willis and Rox arrive at the scene of a road rage accident. Elliot doubts his ability as a doctor when he's sued for his role in the death of a SWAT officer. Leanne discovers Ariel on an ice cream date with a young patient at the hospital.
Over the radio, Leanne and Jesse talk a young girl through how to use the supplies on board a small plane to build a makeshift defibrillator when her mom, the pilot, loses consciousness. Also, Rox and Willis are taken hostage at gunpoint while on their way to meet the plane at the landing site. Julitta Scheel, Marcia Gay Harden's daughter, stars as Ruby Harris, the young girl on the plane.
Willis and Rox are called to the scene of a wildfire in the mountains of Los Angeles to tend to the injured firefighters, and they choose to stay to look for a missing young boy who was separated from his father in the chaos.
Rox decides to make amends with her former step coach when she arrives to Angels Memorial with the local high school step team after a pyramid stunt goes wrong. Also, Noa pleads with Leanne and Campbell to try any other method before performing an emergency hysterectomy on a young teenage girl experiencing complications after giving birth.
Mario joins Rox and Willis on the scene of a boat crash and, in Center Stage, Leanne works to save a brother and sister who drank boiling water through a straw as part of a challenge. Also, Max's father tells Leanne to keep Ariel away from his son after he finds them kissing.
Max is brought to Angels Memorial with breathing difficulty and Ariel tells him she loves him. Also, Rox accompanies Willis and Martin to the funeral of an army buddy of Willis' brother, and Willis decides to get to the bottom of what happened to his brother's unit.
Elliot fears the worst after hearing the emotional testimony by Detective Gomez's wife at his malpractice trial, but hopes footage Diego shot for his documentary will change her mind. Also, Rox attempts to connect with Willis but he pushes her away, and Leanne attempts to comfort Ariel in the wake of a devastating loss.
While rescuing an injured firefighter, Rox is hit by a drunk driver and rushed to Angels Memorial. Willis begins to realize his feelings for Rox and goes to great lengths to help her. Also, Leanne is excited to tell Ariel good news about her adoption.
Willis continues to tend to Rox's medical needs in San Diego and Leanne and Max's father go searching for Ariel. Also, when Noa reveals to Mario she wants to take a job offer in Philadelphia, and Campbell offers Mario the attending position at Angels, they realize their career choices will mean ending their relationship.
Angels Memorial descends into chaos when a plane crashes into the 8th floor. Also, Noa has a car accident and it is up to Mario to save her life. Also, Willis admits to Rox that he needs her in his life and the doctors gather in court to support Leanne for her custody hearing.