TAKING A CLUE from the only writer who’s outsold her, Agatha Christie is about to make her whodunits more friendly to the Hollywood filmmakers whose contemporization of Shakespeare has given the Bard a posthumous resurgence. The Christie estate has made manager Marion Rosenberg the exclusive rep for film and TV rights in the U.S. Her mandate is to bring the tightly plotted mysteries out of the musty, period settings they’ve been stuck in, making them more palatable for cutting edge writers and directors.Christie, who died in 1976, has sold 4 billion books, which her estate said puts her behind only Shakespeare and The Bible as publishing’s most prolific efforts. While some of Christie’s 69 mystery novels and 19 plays have been adapted over the years, her estate has been highly selective and has insisted that films stick to the author’s written words, the settings and the periods in which they were written. That has limited the film possibilities. “Everybody uses the excuse of the milennium for changing what they do, so why not,” said Mathew Pritchard, Christie’s grandson and estate gatekeeper. “The films and TV we’ve done so far stuck to the period when they were written, from the 1920s to the 1960s. Because they have been so glued to the period, they haven’t lately brought out the true nature of her work. My grandmother wrote some wonderful books, and what we want to do is concentrate more on the stories. If that means bringing them up to date, and setting them in the present, that’s what will be done.” Rosenberg said the sales effort came from her attempt to gain adaptation rights to a Christie work for one of her clients. Phil Clymer, managing director of Agatha Christie Ltd. invited her to try to resuscitate film demand for the Christie library. “It’s so exciting to think what can now be done with Agatha, the greatest thriller writer of them all,” said Rosenberg. While films have been made of “Death on the Nile,” “Murder on the Orient Express,” “The Mirror Crack’d” and “Witness for the Prosecution,” many others are fresh territory. Pritchard said the estate will still retain involvement for quality control purposes. “The whole idea is to encourage people to have new ideas, but I wouldn’t think that people would mind a fatherly hand on the shoulder,” he said. “It’s not only a sentimental thing, but business as well. We’ve always made more money selling books than films, and it doesn’t require too many impossible-to-believe films before sales become affected negatively. But we think her adventure stories and whodunits provide infinite possibilities for imaginative filmmakers.” FOX TO REMAKE A “MONSTER”: Who says only obscure old French flicks qualify for American remakes? Fox has just picked up the remake rights to “The Sex Monster,” an American film that was made exactly a year ago. The studio has made a deal with veteran scripter Mike Binder, who wrote and directed the original low-budget indie comedy and starred in it with Mariel Hemingway and Steven Baldwin. The pic’s about a guy whose decision to excite his marriage with a menage a trois awakens his wife’s bisexuality, ruins the guy’s business and pretty much destroys his life. At last year’s U.S. Comedy Festival, “Sex Monster” won Best Picture and Binder won Best Actor, but the pic was only seen on Cinemax and on video, never getting a theatrical distribution. Fox execs Hutch Parker and Tom Rothman considered buying the pic, but instead paid Binder to rewrite it as a mid-sized budget pic designed to appeal to the likes of Ben Affleck and Gwyneth Paltrow. Binder’s repped by UTA and 3 Arts. TUBE INTRIGUE: While he’s stayed away from episodic TV since his celebrated run in “M*A*S*H*,” Alan Alda’s recent “ER” arc has webs salivating over the prospect of a full-time tube return. Dish hears Alda was offered but passed on the ABC family comedy-drama pilot “Wilder Days,” and that NBC is trying to tempt him with a medical show created by John Masius (“Providence”). Alda’s ICM agent Toni Howard confirmed there has been heightened interest, but doesn’t know if Alda will accept a series. “He had an amazing experience on ‘ER,’ but will only return if he finds something of the caliber of ‘M*A*S*H*’ or ‘ER,’ ” said Howard. MORE INTRIGUE: With the clock running out on the contracts of the cast of “Friends,” there has been surprisingly little movement toward extending another season or two. That seems fine with the six stars, who are transitioning nicely to features, as evidenced recently by “Scream 3″ star Courteney Cox Arquette landing the female lead in “3000 Miles to Graceland,” Matthew Perry opening in “The Whole Nine Yards” and Lisa Kudrow toplining “Hanging Up.” While early speculation was that Perry and Cox Arquette’s characters might do a spinoff if deals with their castmates proved too expensive, the cast’s united front and lack of desperation to get to the bargaining table will probably pay off in huge raises. At about $100,000 an episode, the “Friends’ stars are grossly underpaid, given the current value of the show to Warner Bros. and NBC, which would have a cavernous hole in its fall sked without its top-rated comedy. How much can they get? Even though there are six leads, the $600,000 an episode landed by the three “Seinfeld” costars seems gettable, and maybe surpassable, said sources. HECHE-ING HER BETS: If Anne Heche seems scarce in front of the camera since her grisly shower scene in the “Psycho” redo, it’s because she’s been so busy behind the camera. Heche turned down a lead in “The Gift” so that she could promote “Reaching Normal,” the short film she directed which preemed at Sundance, and do media for “2000,” the segment of HBO’s “If These Walls Could Talk 2,” which Heche wrote and directed, with Sharon Stone and Ellen DeGeneres starring. The film preems in Gotham on Feb. 28, and while the ICM-repped Heche will likely take a movie to star in, she’s also looking hard to direct a feature as well.