When she returned home to Salt Lake City last May after a church mission in Paris, Elizabeth Smart glowed as she described her 18 months trying to introduce passersby to Mormonism. Asked by PEOPLE if there was a special guy in the picture, she burst out laughing. "I was on a mission," she said. "That was the last thing on my mind!" Now comes word of a happy development that suggests the 2002 kidnap victim's nine-month period in captivity is well behind her: She's engaged! "We're very excited for her," says her dad, Ed smart. "They've been very happy together." Ed offers no details about the lucky young man, but a source says that Elizabeth, 24, met her fiancé, Matthew Gilmour, who is from Aberdeen, scotland, while she was on her Paris mission, and that romance bloomed afterward. Her rep Chris Thomas confirms only "a summer wedding," adding that the Brigham Young University senior, who is public about her child-advocacy work, "wants to keep her personal life private."