Ever since Sir Arthur Conan Doyle's consulting detective Sherlock Holmes first appeared in print in 1887, speculation has swirled about the relationship between Holmes and his friend and biographer, Dr. John Watson.

While Doyle was clear that the two men were simply good friends - and, indeed, Holmes seemed to have no sexual interest in anybody, and Watson wed his beloved Mary - that hasn't stopped the innuendo.

Especially in the 21st century, where sex has saturated almost every square inch of popular culture, the notion that two reasonably attractive single adults of whatever gender could have a close friendship without romantic overtones seems almost quaint - at least in today's fiction.

When CBS premieres its contemporary take on the classic tale on Thursday, fans of Holmes and Watson will have an entirely new wrinkle in the relationship to tickle their imaginations.

"Elementary" stars British actor Jonny Lee Miller as Holmes, a Londoner whose drug-fueled fall from grace sent him to rehab and then to Manhattan, where he consults on crimes for the NYPD. Fearing a relapse, his wealthy father is forcing him to accept the presence of a sober companion, someone whose job it is to keep the newly drug-free Sherlock on the straight and narrow.

Her name is Dr. Joan Watson (Lucy Liu), a successful surgeon who lost a patient and her license and is seeking to both help someone else and do penance for her mistake.

As to whether a man and a woman can be just friends, Miller says, "Yes, they can. It's certainly possible. They know it to be possible. Of course, they can be friends.

"They might have to have sex, though."

But, as Sherlock's sober companion, it would be a bad idea for Watson to get romantically involved with someone just out of rehab, who is technically her patient.

" absolutely right," says executive producer Rob Doherty. "As far as launching the show, absolutely, it's as unprofessional as you can get, completely wrong and a fireable offense."

But Doherty doesn't insist that this initial dynamic will forever dominate the Holmes/Watson relationship.

"Looking ahead," says Doherty, "and I'm speaking to a hazy notion of what the future might hold, her presence as a sober companion, at least that responsibility, will fade a little bit over time. If we were lucky enough to get into Season 4, 5, 6, I doubt that's what she's there strictly to be."

Doyle built the drug use into his character early on. When the literary Holmes lacks stimulating cases, he seeks to jump-start his brain with cocaine. He also dabbles in morphine, which, like cocaine, was legal at the time.

In the 21st century, cocaine and morphine are illegal, and drug addiction is taken very seriously as a threat to health and life.

"In the books," says Miller, "it's not an addiction, it's just a thing. It was still legal; it was new; and it was something that he did. It's hugely important. It's part of him. It's a problem that's a huge part of his life. It's not something to be taken lightly."

And because of her role, this Watson may have to be a bit more assertive with Holmes than other incarnations.

"If Watson was somebody that he could walk over," says Liu, "there would be no relationship. He has to respect her. If somebody of that intelligence is not going to have respect for somebody, it's going to be a wash."