American teenage witch Sabrina and her food-obsessed magical talking cat and mouse travel to Rome, the last whereabout of her 16th-century aunt Sophia, who was banished after breaking the rule not to divulge her powers to a non-witch; her mission is to find out how Sophia can be freed by opening her golden locket. Sabrina stays with her Italian relatives; notably niece Gwen, an certain and therefore dangerously clumsy budding witch, actually joins her quest there. Being seen using magic, Sabrina gets followed by two tabloid reporters, Paul and Travis, who are promised at least $100,000 if they can expose a real witch, but Paul, an American-adopted Italian, who set out a to win her confidence to trick her easier till they can take a picture of her witchcraft, actually falls in love with her. Gwen has her own Roman admirer, timid Alberto, but impatience for him to make a move causes her to accidentally transform him into a street pigeon. The girls find only one way to Sophia's secret: a portrait by an obscure Renaissance painter, who meant more in auntie's life...