Nestled into a deep red booth at the Musso & Frank Grill on Hollywood Boulevard, Rebecca Rand Kirshner sips demurely from a club soda, heavy on the bitters. She is just three weeks from the finish line on a pledge to go a year without drinking. It’s been a season of restraint: Just last week, the shoe-obsessed writer and co-executive producer of Gilmore Girls finished 100 days without shopping. She quit smoking a year ago this month—although shopping, she says, was much harder.

“Becky knows how to control herself,” her father, Robert Kirshner, the Harvard astrophysics professor and Quincy House master, says with mock seriousness. Kirsh­ner père and Rebecca’s younger brother, Matey, are sampling the restaurant’s signature martinis—gin, up, with olives. Rebecca’s fine with club soda. “I’ve found I can still dance on tables and say embarrassing things without the aid of alcohol,” says the spirited blond, who has a penchant for Edith Piaf, P.D. James books on tape, and Albertus Seba’s 18th-century Cabinet of Natural Curiosities. This was supposed to be a working evening. The elder Kirshner, on sabbatical at UC–Santa Barbara, had been booked for a bit part his daughter wrote into Gilmore Girls, but labor rules required that the spot go to a professional.

So they’re concentrating instead on dinner, no small challenge in a restaurant known for its martinis and literary history—William Faulkner mixed his own mint juleps at the mahogany bar—but hardly for the subtlety of its cuisine. “It’s a very old-fashioned menu,” Rebecca says, wrinkling a freckled nose at delicacies like goulash and chicken pot pie. At work she chugs SmartWater and nips from a bar of Scharffen Berger chocolate. Here, the standards are a bit lower. “I’m trying to settle on something normal,” she says. She comes here for the bookish ghosts. Matey points: “That booth over there is where F. Scott Fitzgerald ruined his liver.” With a skeptical glance at his menu, the elder Kirshner wonders aloud whether the chef, not the alcohol, might have been at fault. “You just breathe and you get the 40-year-old smoke,” Rebecca says, inhaling.

She quickly passes over the low-calorie plate in favor of a New York steak medium rare, with fries and a salad with anchovy dressing. It’s hardly a starlet’s meal—though it’s hard to remember that this leggy, doe-eyed waif in an unhemmed A.P.C. minidress, a rumpled Burberry trench, and gold Prada heels deploys her talent behind the camera, not in front of it. She gesticulates wildly as she talks, as though the thoughts are coming too fast for her words.

But words are her capital. Dinner is punctuated by staccato bursts of laughter and occasional forays into pidgin French, Marilyn Monroe imitations, and discussion of atoms, a real-life version of the kind of dialogue Kirshner has spent the past three years writing for Gilmore Girls.

The show is famous for its silver-tongued banter between mother and daughter; in real life, it’s a father-brother-sister vaudevillian trio, where puns are king and the timing impeccable. Kirshner pauses during dinner to recite a poem she has written for her father’s birthday. It earns raves from her rapt audience. “Genius,” her father says.

Afterward, they head to Star Shoes, a narrow, funky bar favored by Hollywood’s artistic set. A small posse of writers and artists is crowded into a booth at the back, talking quietly, when Kirshner arrives to show off her dad and celebrate (her 32nd birthday, his 57th).

Her crew is an intellectual one, with many holdovers from her Adams House days—writers Billy Hulkower and Michael Sonnenschein, musician and web designer Roni Brunn. Kirshner’s ex-husband, Daily Show co–executive producer Josh Lieb, is not on tonight’s guest list, though they remain friendly.

Kirshner squeezes in next to Jane Espenson, a friend from her pre-Gilmore years at Buffy the Vampire Slayer, and introduces her dad. Her friends are adoring. “She walks into a room and you think she’s a fashion model,” Espenson says. “But she’s thought on a more academic level about writing than any of us.” Kirshner rises to greet a new arrival, former Blue Man Andrew Burlinson, then fellow Gilmore Girls writer Jennie Snyder. Kirshner wanders from group to group, captivating each. “You think she’s like Anna Wintour,” Sonnenschein muses. “Then she opens her mouth and you realize she’s like Joseph Stalin. She exerts control over her social milieu with an iron fist.”

On the dance floor, a break-dancer goes at it alone. Rebecca tries to lure her father into the action. “I’m on a sabbatical from dancing,” he quips. But soon he’s kicking in time to the tripped-out hip-hop.

Rebecca joins in, and they break into a modified Charleston. Pretty soon everyone is watching them shimmying, shaking, crossing their knees in true ’20s style, and boogying their hearts out.