In the premiere, a former military doctor deals with a life-threatening situation on his way to work; his ex-girlfriend pursues the night shift's top job; and a clash over business matters unfolds.

TC desperately tries to save his critically injured friend. Meanwhile, Paul tackles a challenging case involving an elderly woman; Kenny helps an injured groom with a secret; and a 9-year-old boy has suspicious injuries.

TC and Paul race to the chaotic scene of an after-dark hog-hunting event that has gone nightmarishly wrong. Meanwhile, a 9-year-old girl arrives for treatment in a case that turns complicated; Drew injures his hand; and Ragosa seeks family counseling.

Injuries at an Alamo reenactment test the staff. Meanwhile, a disoriented patient suffering from amnesia receives care; Drew helps a severely wounded soldier; Topher schedules a vasectomy operation; and Jordan's boyfriend arrives.

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 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.

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 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.

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.

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

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

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

A building collapses during a rodeo; a severely injured cowboy exhibits strange symptoms; Scott causes a serious car accident.

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

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.

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.

The overnight crew becomes immersed in a bizarre car-accident rescue. Drew serves overseas in Afghanistan and teams with a colleague to treat an Afghani woman, A spunky grad joins the shift.

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.

Drew stressfully adjusts after returning from deployment in Afghanistan. A bride and her wedding party are treated for injuries sustained during the festivities, and Topher's demanding mother pays a visit.

As the city erupts in violence over an impending jury verdict, the night shift becomes ground zero when they have to take in the man suspected of the racially-motivated shooting at the source of the unrest. His presence in the emergency room sparks sharp conversation and disagreements among the staff over the highly-charged topic and even close friends Kenny and Paul find themselves at odds. Topher does his best to control the mounting chaos in the ER while out in the field, TC makes a decision as to which of two patients to bring in, leaving Paul and Scott to question TC's motives.

A college co-ed falls from a balcony and once she is in the ER, TC and Paul find that her situation is even more complex. Jordan bonds with a terminal patient who teaches her some important lessons about living. TC's errant sister-in-law Annie returns and hopes to make amends. Meanwhile, Jessica - a pharmaceutical rep with cutting-edge equipment that Scott is so close to getting for the hospital - if her tension with TC doesn't kill the deal.

Shannon and Jordan venture out for some fun at a local wrestling event only to find themselves treating people on site when a fight breaks out amongst the audience. Back at the hospital, Sam attends to a marathon runner who has collapsed from the heat and things start to heat up even more when the air conditioning breaks. Meanwhile, tensions between TC, Jordan, Sam, and Annie start to boil.

A fireworks explosion creates chaos at a concert, sending patients streaming into the hospital as TC and Topher race to the scene. Syd returns from Afghanistan and faces her unique family dynamic. Jordan and Scott address simmering differences.

The doctors race to save Topher's mom when she comes to the ER with life-threatening symptoms. The team discovers a gravely injured foster mom is harboring a secret. Jordan asks T.C.'s girlfriend for help with a patient.

When a bomb explodes outside the hospital, TC, Topher and Drew are forced to make the tough decision to stay and treat the injured or evacuate and begin transfers to nearby hospitals. Everything changes when TC suddenly realizes he may know the person responsible for the explosion. While the team works feverishly to tend to the wounded, the nurses go on strike just when the hospital needs them the most. Meanwhile, throughout the intense night shift, Shannon and Paul attempt to confront each other about something personal.

TC and Paul pull out all the stops when a crane collapses on a worker at a busy construction site. As Paul works tirelessness to save the crush victim, an observer falls into a deadly gravel pit. TC throws himself into the pit and races to save the patient before he's swallowed by the shifting gravel. Back at the ER, Scott is shaken as the teenage boy he paralyzed returns to the hospital with new complications. Jordan lends support as the emotional case exposes complicated feelings from the past. Meanwhile when a life-saving donor matches with cystic fibrosis patient, Brianna, Drew determines the depth of his feelings for her.

TC initiates a bar brawl, landing him and Drew in jail for the night. While behind bars, Drew and TC's relationship reaches a breaking point. Jordan rushes her date to the ER, where she's shocked to learn he's not who she thought he was. Topher fights for a patient who many doctors have dismissed. Scott and Annie struggle to save their relationship while Jessica works to win back TC's trust. Meanwhile, Syd meets Brianna, and Rick visits the hospital.

In part one of this two-part season finale, Scott and Jordan face grave danger during a rescue mission at a rapidly spreading wildfire outside San Antonio. Tensions are high between Syd and TC as they find themselves in the middle of a humanitarian crisis on the Syria-Turkey border. Paul and Shannon argue over treatment for a patient. Meanwhile a major setback threatens Drew's adoption plans for Brianna, Topher struggles to find a buyer for the hospital and medication goes missing.

Scott and Jordan must perform surgery in the field as the burning wildfire gains intensity around them. Syd has caught Typhus along with hundreds of other patients on the Syria-Turkey border, and TC goes to great lengths to get the medication. Meanwhile, Drew and Rick fight to keep Brianna, while San Antonio Memorial finds an unlikely buyer, though saving the hospital comes at a cost.