"The Mirror Crack'd," a film version of the Agatha Christie murder mystery packaged by the same producers responsible for "Murder on the Orient Express" and "Death on the Nile," begins auspiciously:

We find ourselves watching a bogus old British mystery film just at the point where a police inspector, adroitly played by Nigel Stock, arrives at a mansion to sort out the well-bred suspects. He prepares to announce the murderer, and the film breaks, disclosing our real setting, a social hall at a vicarage.

The anxious vicar, doubling as projectionist, promises to repair the injured reel of "Murder at Midnight." One member of the audience is not prepared to wait. As she gathers her things and takes her leave, frustrated viewers solicit her opinion about the identity of the killer. With an air of genial authority, she briskly disposes of several possibilities and states the case for her candidate. Frowning, one man turns to another and remarks, "She could be wrong, you know." His companion replies, "She's not. I've seen the picture."

The astute lady is Mrs. Christie's famous amateur sleuth Miss Jane Marple, and this sequence is a capital introduction to both the character and actress Angela Lansbury, assuming the role played in a popular series of films two decades back by the late Margaret Rutherford. A more suitable physical and temperamental choice, Lansbury enlivens the role with an alert, keenly intelligent presence and ginger-snappy line readings. She's so attractive in the role that it comes as a letdown when "The Mirror Crack'd" begins to lose its edge and broaden its humor until the mystery plot collapses in a rather ludicrous heap.

The story is set in 1953 in Miss Marple's placid hometown, where a movie company has set up camp to shoot a production of "Mary, Queen of Scot," with an actress named Marina Gregg attempting a comeback in the title role while her professional nemesis, Lola Brewster, plays Queen Elizabeth as a brash, buxom wench. During a reception at the country estate rented by the director, a local clubwoman dies inexplicably of poisoning. The title is drawn from Tennyson -- "The mirror crack'd from side to side/'The curse is come upon me,' cried/The Lady of Shalott" -- and provides an esoteric clue to the mystery. (The murder case was entirely Christie's fiction, but the encounter that triggers it was inspired by something that actually happened to Gene Tierney.)

Unfortunately, the focus of the story is allowed to shift from Lansbury to the former Hollywood luminaries cast as the principal suspects, envisioned with extreme facetiousness: Elizabeth Taylor as actress Marina Gregg; Rock Hudson as her director husband Jason Rudd; Kim Novak as Lola Brewster; and Tony Curtis as Lola's Sammy Glickish producer husband Marty N. Fenn, one of the total inventions of screenwriters Jonathan Hales and Barry Sandler.

The intramural show-biz insult festival that attends the introduction of the movie personalities is allowed to hog the screen and ultimately undermine the murder mystery. Kim Novak in particular has been encouraged to camp it up, hurling one sarcastic jest after another at Taylor, who must be accounted a Real Good Sport for permitting remarks as unflattering as "You've not only kept your adorable figure but added so much to it!"

The bitchery may be funny for its own sake, but it causes the film to lose touch with its real heroine and genre. Moreover, the Christie plot ends up so drastically foreshortened that you'd swear a reel must have been misplaced, although the sluggish direction of Guy Hamilton doesn't make one anxious to see it restored.

Edward Fox seems an admirable choice as Miss Marple's nephew, Scotland Yard inspector Dermot Craddock, but why was he allowed to indulge in so much delayed-action frowning and mugging? Surely the character calls for a spotlessly dry, attentive, ironic interpretation. The producers' calculations also baffle me. Could they be correct in their apparent assumption that moviegoers want more of the over-the-hill movie stars camping it up than the great character actress taking brisk command of an appealing new role? I hope they don't know what they're doing.