Los Angeles Times
The purr-formance: Pyewacket is the familiar (a supernatural being who helps a witch or magician) of a witch named Gillian (Kim Novak). When Gillian sets her sights on a mortal (Jimmy Stewart), she sends Pyewacket to work his magic on the bachelor.
The cat's meow: Stewarts character is allergic to cats and gets peeved when Pyewacket, a blue-eyed Siamese, constantly rests on his shoulder. At one point he tells Gillian, Can we fix this cat a drink or something?