'Mystery!' spotlights the romantic side of the 'queen of whodunits'

Britain's famous ''queen of whodunits'' was also a ''queen of romance.'' The world knows Dame Agatha Christie as the author of around 85 crime novels, which sold more than 350 million copies. Hercule Poirot and Jane Marple were creations of this imaginative writer. But what most people don't know is that Agatha Christie was also responsible for more than 150 short stories, many of which were romances and fantasies. She wrote at least six romantic novels under a pseudonym as well.

Now, some of that amazing ambivalence is being revealed to American TV viewers in a remarkable four-hour miniseries based on Dame Agatha's short stories as part of the Mobil-funded Mystery! series (PBS, Thursdays, 9-10 p.m., Feb. 17-March 10, check local listings).

The opening story, ''The Manhood of Edward Robinson,'' is the most romantic of the group, combining suspense and romantic fantasy with just a touch of madcap farce. It even has a rather charming impressionist dance sequence. The succeeding tales all concentrate on high-society romance, tinged with a trace of imaginative caprice. Not all of it works, but enough works well to reward viewers - both Christie fans and uncommitted audiences - with slick, skillful Thames TV views of the other side of Dame Agatha.

At lunch with Pat Sandys, the producer of Thames's ''Agatha Christie Hour'' who has now become one of England's greatest authorities on Christie, I learned that Dame Agatha was never very happy about the film adaptations of her work, except for ''Witness for the Prosecution.''

Does Ms. Sandys feel there is an identifiable Agatha Christie view of society?

''No, I don't think society with a capital S interested her very much. Human beings fascinated her. And I think that these stories (there are still six more which may appear on PBS later) reveal her enormous understanding of human nature more than the novels and films. She was a very wise woman but very shy. She couldn't bring herself to walk into a reception in a restaurant. She hated large parties. She was a very private person although she obviously watched people all the time.

''I've spent so much time with her work that I have gotten a kind of instinctive feel for the woman herself. When we were filming, quite often I would hear myself saying 'We can't do it that way; Agatha wouldn't like it.' ''

I sometimes confuse Margaret Rutherford, who played Miss Marple, with Dame Agatha herself. Were they alike at all?

Ms. Sandys shakes her head vigorously. ''Although I never met Agatha Christie , I did work with Margaret Rutherford. Agatha in her younger days was reckoned to be an extraordinarily handsome woman; Margaret never could have been. But, they did have in common a very intense femininity. Agatha was never a feminist - in her autobiography she said that modern women have it all wrong. Margaret Rutherford was always interested in very feminine clothing and things of that sort.''

Ms. Sandys says a biography of Agatha Christie is now being written by a very distinguished British writer, who has been given access by the Christie family to all sorts of private papers. ''She herself only wrote two nonfiction books - her autobiography, called 'Autobiography,' and the other called 'Come Tell Me How You Lived,' about a dig she went on with her archaeologist second husband. In that book she reveals more of herself than in her autobiography.

''What an extraodinary woman! She was a working writer for over 53 years. And most people don't realize this - hers was the richest literary estate ever.''

Somehow I have the feeling that the Agatha Christie/Pat Sandys collaboration is far from over. Next project - a filmed biography of the queen of whodunits and romance?