A new heart-stopping medical drama premieres on CBS tomorrow, Sept. 30. Set in "the busiest, most notorious ER" in Los Angeles, "Code Black" will give viewers an idea of what it looks like when patients outnumber the hospital's resources, doctors and nurses.

While such situation is not at all unprecedented in hospitals, Angels Memorial Hospital is unique as it goes into code black 300 times per year, a ton of times more the average, which is only five. This is what the show will emphasize in the pilot episode.

When "Code Black" premieres, viewers will be introduced to residency director Dr. Leanne Rorish, who is played by Marcia Gay Harden. Rorish keeps the chaos contained there as much as possible. She usually works her magic in Center Stage, where the most severe and high-risk cases are dealt with.

In this area, everything relies on the doctors and nurses' quick thinking and skills. The chances of survival are so elusive that the ones who get out of there consider it a miracle. In a way, Rorish has been a miracle worker.

"I liked that they weren't making this sort of, 'Hi, I'm a television doctor,' " Harden told Toronto Sun of her character in the new series. The Oscar-winning actress added that she loves "Code Black" for being "docu-style." The series was actually inspired by a documentary of the same name.

Rorish will be in charge of escorting four new first-year residents, namely Christa Lorenson (Bonnie Somerville), Malaya Pineda (Melanie Chandra), Mario Salvetti (Benjamin Hollingsworth) and Angus Leighton (Harry Ford) on their first day at the ER.

"Code Black" will also see Rorish's welcoming confidante, Jesse Sallander (Luis Guzman), who will be in charge of supervising the newcomers. While Rorish is regarded for her performance at the hospital, physician Dr. Neal Hudson (Raza Jaffrey) finds it a bit like a "cowboy approach."

Lastly, the new hospital drama will acquaint viewers with Dr. Rollie Guthrie (William Allen Young), who never seems to lose his vigor and passion in serving even after attending at the ER longer than almost anyone else.