Col. Ethan Willis joins the team as part of a program in which the Department of Defense sends doctors to hospitals to teach new techniques.

On Halloween night, Willis, Noa and Elliott rush to the scene of a fire at a haunted theater, where Dr. Nolan (Kathleen Rose Perkins) and her boyfriend's son are trapped.

The Angels Memorial doctors treat victims caught in a landslide, and a group of children come in from a camping trip with measles putting the entire ER at risk. Meredith Baxter and Eric Roberts guest star.

Malaya must inform a college student that she's been raped, while Willis and Campbell argue over a terminally ill woman who wishes to die on her own terms.

Willis and Campbell are sent to a Russian submarine in U.S. waters to treat a sailor badly wounded during an explosion, and violent convicts injured during a prison riot descend upon Angels Memorial.

The doctors treat cult members who unwillingly survived a mass suicide attempt, and Mario decides to connect with his late father's girlfriend.

A city-wide blackout leaves Angels Memorial without power or back-up generators.

Against Campbell's orders, Leanne uses the hospital helicopter to reunite a family one last time.

Guthrie considers an experimental surgery to treat his Parkinson's while adjusting to his new position as the hospital chaplain.

Mario follows Willis to a construction site to save two brothers trapped in a crane 300 feet above the ground.

A viral outbreak jeopardizes the doctors and patients of Angel's Memorial.