Joss Barratt/CBS

On her hit show, Elementary, Lucy Liu’s doctor-turned-detective unravels mysteries. Offscreen, she prefers to remain one.

IT'S A CLEAR, BRIGHT DAY in New York City when Lucy Liu slips into Petite Abeille, a small bistro in the heart of Chelsea. Wearing a vintage sundress with an embroidered smock, Liu seems oblivious to the unfeigned gazes of admiration from patrons as she wends her way to my table and introduces herself.

“I’m Lucy,” she says, extending her slim hand in greeting. Her lustrous onyx tresses frame a freckled face bearing not a stitch of makeup, looking much younger than her 44 years. She wears no jewelry; not even a timepiece adorns the wrist that has wielded samurai swords, blowtorches and sawed-off shotguns in her more-than-20-year career as an actress. Best known for playing formidable chicks in roles such as O-Ren Ishii in Quentin Tarantino’s Kill Bill films, Alex Munday in the 2000s’ Charlie’s Angels franchise and Ling Woo on Ally McBeal, Liu is nothing in real life like her on-screen personas. No more than 5 feet 3 inches tall in flats, she is down to earth and friendly to effusive fans and waitstaff alike.

I quickly deduce she is smashing. Elementary, my dear Watson.

In this instance, that’d be Dr. Joan Watson, the character Liu plays on CBS’ hit series Elementary, a modern-day adaptation of the Sherlock Holmes detective series that takes place in the gritty, glittering city of Manhattan. Starring opposite Jonny Lee Miller as Holmes (here a recovering addict with tattoos), Liu’s Watson is a disgraced surgeon who has been hired as the detective’s live-in sober companion by his wealthy father. At first, the prickly Holmes is insolent toward his new minder, but it’s not long before he warms to her no-nonsense intellect, and the duo is off solving its first crime.

“As a female, I think you have to have a very strong sense of yourself in order to relate to someone like that,” says Liu, sipping a mug of mint tea. “If he doesn’t respect you, if he doesn’t think you’re intelligent, then he’s finished with you in three seconds.”

That said, it doesn’t take a genius to figure out why show creator/executive producer Robert Doherty cast the unflappable Liu in the iconic role of Watson, which up until now has only been played by a mustachioed man in a trenchcoat. “Her work speaks for itself,” he says, noting that Liu’s “grounded” portrayal of Los Angeles police officer Jessica Tang on Southland is what convinced him that she was his Watson.

“I wouldn’t be surprised if Lucy was a doctor in another life,” Doherty says of Liu’s ability to convincingly play a trained sobriety counselor and ex-surgeon. “As far as keeping up with Sherlock, Lucy can do that in her sleep. We needed intelligence, humor and a woman who could banter with him. Based on everything I’d seen [prior to casting], Lucy was a slam dunk.”