T.C. and Topher return to find Jordan in critical condition and San Antonio terrorized by snipers; Drew and Gwen get caught in the crossfire when a SWAT team corners the snipers.

When protestors descend on a funeral for a dear member of the night shift family, multiple veterans are injured and brought to San Antonio Memorial for treatment. A high profile politician from Drew's past triggers flashbacks to his time in Iraq. Jordan, Scott, and TC disagree on how to best provide care for the politician. Paul and Shannon must improvise while tending to Doug, a former POW. Cain and Drew treat a fearless photographer.

Drew and Paul head to the scene of a multi-car collision while the newly-anointed Dr. Ragosa along with Jordan, Scott, Krista and Kenny, manage the deluge of incoming victims. Meanwhile, TC and Topher head into a war zone to treat an old friend.

A boy is suffering with a serious fever and his high-strung mother begins to show signs of distress.

A horrific crash sends dozens of soldiers, including Drew's boyfriend, to the emergency room, where TC and Scott clash. Meanwhile, Topher tries to diagnose a soldier's illness, and Kenny tries to improve Ragosa's online-dating profile.

TC and Topher treat the lone survivor of a plane crash while fending off an intimidating law-enforcement officer with a secret motive. Meanwhile, Paul is smitten by an injured exotic dancer whose condition takes a turn for the worse; and Krista cares for a teen with an eating disorder.

A shoot-out in the ER leaves Topher seriously wounded. TC tries to control his Afghanistan flashbacks. An explosion at a fertilizer factory sends burn victims to the ER, overwhelming the shorthanded staff. And Jordan discovers a secret about TC.

TC and Scott fight to save a boy and his mother who were injured in a car accident, yet it becomes clear there's more to the family dynamic than meets the eye. Deployed in Afghanistan, Drew and Syd face the aftermath of an OR shooting.

A violent storm pummels San Antonio, sending numerous patients to the emergency room. Elsewhere, TC and Dr. Scott Clemmens rush to a mudslide disaster to treat a mother and her son; and Topher braves the storm to help his stranded wife, who's going into labor with twins.

A serious car crash results in two teens and a young pregnant woman arriving at the hospital, pushing the night shift members to their limit. Meanwhile, Paul tends to a quirky, wealthy hospital benefactor.

Drew takes action when a gunman attacks at a friend's promotion ceremony.

Jordan and Drew perform a daring rescue by jumping from a chopper. Landing at the nearest VA hospital, Jordan sparks a plan to appease Julian and reunite her night shift team. Back at the hospital, Paul deals with the repercussions of standing up to his father while Scott dives headlong into his professional life. Kenny butts heads with Cain, a traveling nurse with a mysterious past. Shannon indoctrinates Cain as they work in San Antonio Memorial's understaffed and overworked ER. Meanwhile, TC is held captive in Syria. In order to find Syd, TC must treat his captor instead of returning to the safety of an air base with a civilian volunteer, Amira.

Drew, his mom, and Rick's flight home turns into a medical crisis at 35,000 feet when passengers become sickened one by one. Jordan, Paul, Shannon, Kenny, and Cain spend their day off at an obstacle course fundraiser for Cystic Fibrosis, hosted by Akbar Gbajabjamila. Scott finds himself on a Tinder date he won't soon forget. Meanwhile, TC puts his own life in danger to operate on a soldier.

Kenny joins Drew at his MMA veteran's support group and finds himself in the fight of his life. Jordan and Cain treat casualties from a hotel fire while Shannon follows a hunch to help save a young victim. Paul's superstar sister, Dr. Bella Cummings, pays a visit to San Antonio Memorial. Meanwhile, TC finally returns home, forcing him to deal with Topher's death.

Topher takes over as chief of the night shift. TC is temporarily suspended. Jordan is scrutinized for her mishandling of the man who shot a recovered Topher. A father is trapped under an elevator. Ragosa returns to the ER.

The night shift is tested when a rancher accidentally shoots his wife. TC heads to a teen party to save the life of a young football star. Jordan and Kenny treat a beauty queen in severe distress. Topher makes a decision about his job.

A downtown gas explosion sends dozens of casualties to San Antonio Memorial Hospital.

Jordan and Krista offer roadside assistance to a motorcycle crash victim.

After performing a daring on-site rescue to save a teenage girl, Drew is forced to re-evaluate his priorities as a new father. Back at the hospital, the ER is flooded with mass casualty victims from an amusement park disaster. Hoping to get Paul back on staff, Jordan facilitates a rapprochement between Paul and his father. Meanwhile, Scott pursues a more active role in the hospital and Kenny tries to put Cain in his place.

Jordan and Cain figure out their professional dynamic as they work on a patient with extreme injuries from an oil field explosion. Drew and Paul receive a patient from the same accident, and must figure out a solution to save the patient's severed hand. Scott is caught off guard when Annie shows up to the hospital with an unexpected guest from his past. Kenny and Shannon struggle to adjust to their new living situation. Meanwhile, TC and Amira clash over treating a Syrian child on the American base.

A shooting at a nearby college sends TC, Jordan, Drew and Amira into the field, where they assist Rick with a deadly situation. Scott implements a new training program and locks horns with Julian. Drew struggles with frustrations about going to Army Ranger School while Shannon and TC both contemplate their future at San Antonio Memorial.

An injured skydiver is rescued, but there's more to the case than meets the eye. Meanwhile, the night-shift staffers treat an electrocuted janitor, then scramble to save his wife and children when they fall ill to life-threatening symptoms; and Paul learns about his limitations as a doctor.

A patient arrives with radiation poisoning, spinning the night shift into chaos and putting it into lockdown. Meanwhile, staffers speed to a serious car crash, where they discover an injured police officer, TC's troubled sister-in-law visits, and a former patient harasses Jordan.

As a thick fog descends upon San Antonio, the doctors must improvise to save the victims of a car crash; Topher, Drew and Kenny treat siblings injured in the fog.

T.C. discovers his sister-in-law's complicated history after he treats her for a fall down stairs.