The font of all this fervid storytelling is Rhimes, who, at 43, is often described as the most powerful African-American female show runner in television — which is too many adjectives. She is one of the most powerful show runners in the business, full stop. Rhimes is among the few remaining bona fide network hitmakers; her pull at ABC is matched only by Chuck Lorre, with his three sitcoms at CBS, or Seth MacFarlane, with his three animated shows at Fox. Before “Scandal,” Rhimes created the hit medical drama “Grey’s Anatomy” and, later, the sudsier “Grey’s” spinoff, “Private Practice,” which ended this past January after a six-year run. Channing Dungey, who oversees ABC’s drama development, describes Rhimes as “incredibly important” to the network. “If she came in tomorrow and said, ‘I have a great idea,’ I would jump at it.” Since 2009, ABC has given over its Thursday-night lineup to a solid two-hour Shonda Rhimes programming block.

Sitting behind her expansive desk, Rhimes continued to go through the script with her writers, finessing dialogue, addressing continuity errors and looking to sharpen the trademark “Scandal” tone. A writer noticed that the phrase “Cyrus is the mole” was repeated four times in an exchange. Rhimes told him not to worry. “It’s the rhythm of the conversation,” she said. “It’s going to be sexy. Trust me.”

As part of her Shondaland production company, Rhimes oversees some 550 actors, writers, crew members and producers, and her days are optimized to do so. In the morning, she gets her older daughter, Harper, who is 10, off to school and then contends with whatever is most urgent: writing, giving notes on a script and watching casting videos. The televisions in her office and home are connected to a system that allows her to watch real-time editing by her editors. Both of her daughters have rooms across the hall from her office at work. The younger, a perfectly chubby-cheeked 1-year-old named Emerson, comes in every day, clambering onto Rhimes’s lap during meetings.

As she does her rounds, Rhimes says hello to strangers in the elevator and tells one director, working late into the night, “You are so pretty and talented.” But she also has a no-nonsense authority, a matter-of-fact bluntness. After a discussion with her writers in her office goes on longer than she wants, she breezily ends it: “Don’t talk about it in here anymore. I’m done.” Not long into the first season, she said, she stopped taking network notes on “Scandal”; eventually, ABC stopped giving them. “What was great for me about ‘Scandal’ was I had earned a lot of political capital with the network,” Rhimes told me. “I had done ‘Grey’s,’ I had done ‘Private Practice.’ What were they going to do, fire me? I wasn’t worried about what anybody else thought. This one was for me.”

The sure manner with which Rhimes wields her power did not come naturally; it’s something she had to learn. Born in 1970 and raised outside Chicago, she is the youngest of six; her mother was a teacher who got her Ph.D. after Rhimes left for college, and her father is now the chief information officer at the University of Southern California. She un-self-consciously describes herself as a Tracy Flick-type, a good girl with her hand always in the air or her nose always in a book. After graduating from Dartmouth, she read an article in The Times that said getting into U.S.C. film school was harder than getting into Harvard Law and thought, This sounds like a really competitive thing to do. I’m going to do it.