British actress Lindsay Duncan enjoys time travel. A classically trained stage actress ("Les Liasons Dangereuses") she also works in television ("A Year in Provence," "The Rector's Wife," "Tom Jones") and film ("An Ideal Husband," the upcoming "Mansfield Park"). And in choosing roles, she flits between the past and the present.

"I am more at home in a corset than I am in a pair of jeans," she said recently from New York, there to publicize Sunday's "Mobil Masterpiece Theatre" production, "Shooting the Past."

In this two-part story, airing at 9 on PBS and concluding Nov. 28, Duncan plays librarian Marilyn Truman, who lives for her job and is a sort of mother figure to her quirky staff. "Shooting the Past" is half-mystery, half-drama, set among 10 million rare photos.

When the story opens, Truman learns that an American company has bought the mansion that houses the collection. A Mr. Anderson, played by Liam Cunningham, arrives, bewildered that the place isn't ready for bulldozing to make way for his business school. The two quickly clash. The house should have been vacant, Anderson tells Truman; throw the photos away. There must be a misunderstanding, she responds; it's a priceless collection and needs a new home.

Duncan described her character as "a self-sufficient, proud, intelligent woman who clearly finds her job stimulating and satisfying and she feels very, very strongly about it. And I think she's compelling in that she is so uncompromising."

Anderson gives Truman a mere week to find a buyer for the collection, so she and her staff weave suspenseful stories using the photographs to convince Anderson of their value. Their ruse begins to work: The first tale, about a little girl evading the Nazis, leaves him clinging for the outcome.

The whole matter is further complicated by Timothy Spall's eccentric Oswald Bates. Another librarian, Bates has, appropriately, a photographic memory. He also will do anything to keep his job in spite of the business-minded Yanks. In their defense, said Duncan, "You'd be upset if you'd bought a house and it was full of people." The line between the good guys and bad quickly blurs.

"Shooting the Past," written and directed by Stephen Poliakoff, is based on a true story. Poliakoff had a friend, Duncan recalled, who worked at London's MGM Studios, which had a huge photo archive. The studio was sold and the new owners said they would burn the building. Thankfully, the George Lucas Foundation bought the collection, she said.

Duncan found Poliakoff's script compelling, both for the characters and for the fact that it skips "the very common ingredients of sex and violence." Instead, the story is about connection with the past, a reminder that "the kind of connections made in the world are extraordinary and commonplace," she observed.

The movie raises other questions, said Duncan: "Hovering at the end of the millennium, what do we value? Is there a place for oddballs in this world? People with brilliant but unconventional roles like Oswald? In my opinion, we need it all."

Although "Shooting the Past" is a contemporary tale, Duncan's other recent roles have all revived the past. She plays Lady Bertram in the Jane Austen film "Mansfield Park," opening nationally Dec. 25. She also just finished a production of "Oliver Twist" that will air on "Mobil Masterpiece Theatre" next year.

"In the slightly murky world of movies, working in the theater gives me my dignity," she said. "You're pretty much cannon fodder in the world of movies. Ideally, I like to do a good mix because it's just more interesting." In 1987, she was nominated for a Tony for her role in "Les Liasons Dangereuses."

Duncan is married to actor Hilton McRae, who is currently on stage in London's West End in "Mama Mia," which she said is due to come to New York. They have an 8-year-old son, Cal, who despite having two parent actors, would rather be a soccer player, she suspects. "I'd like him to be in the arts, because I believe in the arts passionately," she said. "It's important for the well-being of a society."