Pittsburgh's 350,000 residents come from all walks of life, but tragedy can strike the lawyer or the steelworker. It is in these times of greatest need that people can depend on the doctors and nurses at Allegheny General Hospital. Here the staff will see: a man ejected from a car after it crashed; a newborn baby suffering from seizures; and an injured Cirque du Soleil acrobat.

Every day, the staff at the University of Oklahoma Medical Center is faced with the consequences of sudden and devastating trauma. Frequently, they must deal with issues surrounding head traumas, and in this episode, you'll see a 23-year-old Air Force sergeant just back from the Middle East who's been shot in the head, and a teenage boy who's been declared brain dead after a car crash.

It's nighttime in Pittsburgh. The skyline shimmers, the streets are quiet, and most people are safely at home. But there are always those who are in the wrong place at the wrong time, making mistakes. Across the river from the skyscrapers, the doctors and nurses at Allegheny General Hospital work tirelessly all day and night to repair the mistakes that others have made. In Night Calls, Dr. Ryan Flesher races to save a man who has overdosed, while Dr. Melissa McLane comes to the aid of an elderly woman with a shoulder fracture and three young men who were attacked in a bar parking lot.

Las Vegas is a city where life is an endless gamble. And the staff of its University Medical Center are there for people when the stakes grow too high and lady luck runs out. In this episode, patients include: a soccer player with a deep laceration under his toe; a 2-year old with the croup; and a young deaf boy who was hit by his neighbor's car.

You never know when trauma may strike. For those injured while simply going about their daily lives, waking up in a hospital bed days later can be terrifying and confusing. That's why the staff at Portland's Legacy Emanuel Hospital not only saves patients, but helps them rebuild their lives. This episode's patients include a toddler who's suddenly developed a severe infection on her face, an elderly man facing lung disease after a lifetime of smoking, and a young mother and daughter who were struck by a car.

Detroit, Michigan. The center of America's automobile industry. Life can change in an instant on the fast-paced highways and streets of the Motor City. When it does, the crew at Detroit Receiving Hospital stands by to repair and revive the injured and critically ill of this Midwest metropolis. In Motor City Blues, the doctors and nurses treat a man who shot himself in the mouth, claiming he was kidnapped by the same men who murdered his wife.

Detroit, Mich. has had its share of tough times. Decades of unemployment and crime have taken a toll on the city. Now, many of its citizens are rolling up their sleeves to dust off this once vibrant metropolis. Similarly, the doctors and staff at Detroit Receiving Hospital devote their time to restoring patients to their former selves. In this episode, the staff examines a patient who jumped out a second-story window after a drug deal went bad, a man who was bitten during a brawl, and a 32-year-old who fell after trying to hop a freight train.

Oklahoma is a land of heroes past and present. "Never say never" is a motto that describes its citizens, as well as the medical staff at the University of Oklahoma Trauma Center, who never say "never," even to the most severely injured patients. Among those in need of care are a man who fell off his motorcycle at 75 mph and requires a triple amputation, a woman who fell into a sewer hole, and a patient who was pinned under his tractor for several hours.

With its thrilling attractions, endless sunshine and miles of shoreline, every day in Orlando, Fla., can feel like a holiday. But Orlando's many citizens and visitors are not immune to tragedy, and when it strikes, they turn to the staff at Orlando Regional Medical Center for help. At the Tragic Kingdom you'll find a drunk driver who crashes into a family on their way to a fishing tournament, a patient critically burned in a mattress fire, and a man who's punched a plate-glass window.

From riots to drive-by shootings to high-profile drug overdoses, Los Angeles has seen its fair share of trauma. In "Unbreakable," you'll witness the doctors and nurses of Martin Luther King-Drew Medical Center tending to a little boy having a seizure, a patient coughing up blood, and a young man who's been shot several times.

The peaceful city of Portland, Ore., boasts one of the highest safety ratings in the country. Here, even swimming alone is illegal. But accidents will happen, and when they do, it's the doctors and nurses of Legacy Emanuel Hospital who come to the rescue. The patients here include a 69-year-old shot in the stomach by his wife, a woman suddenly paralyzed because of a blood clot, and a confused patient who is wandering the hospital naked.

In the world of level one trauma, medicine can be all it takes to save lives and avoid tragedy. But often there are individuals with such terrible injuries that medicine alone can't be called as the cure; unfortunately, survival can often be a matter of fate. At Orlando Regional Medical Center, doctors learn to treasure each and every save — the miracles that keep them striving against all odds. In this episode, the staff sees a 6-year-old whose seat belt has crushed her in a car crash, a man stabbed in an argument over a neighbor's loud music, and a young man shot in the head during a road rage incident.