PBS's ''Masterpiece Theatre" usually delivers adaptations that don't involve a lot of chasing through forests and crossing of swords. If there's any heavy breathing in the franchise's hollow mansions, it's probably the result of villainous words or eye-poppingly tight corsets. The action sequences, such as they are, generally require only teacups, spoons, and silver tongs.
''Kidnapped," a two-parter premiering tomorrow at 9 p.m. on Ch. 2, is based on Robert Louis Stevenson's adventure yarn set in 1751, after England's occupation of Scotland. It's not your typical ''Masterpiece Theatre," but then neither was last week's spin on Sherlock Holmes starring Rupert Everett. It's the PBS version of a youth-market grab, a jaunty buddy movie whose heroic pair aren't quite models for teeth-whitening products. ''Kidnapped" has a lot of good energy and likable acting; but it might be more appropriate as a family matinee rather than as a Sunday-night feature. It has rainy Sunday afternoon written all over it.