Size Twelve Is Not Fat
Size Twelve Is Not Fat is the first novel in Meg Cabot's Chick-lit Mystery series featuring former teen idol, Heather Wells. Recently dumped by her fiance (learning they'd broken up when she discovers him with her replacement) and recently poor when her mother makes off with her money, Heather strikes out on her own and gets a real job: as an Assistant Residence Hall Adviser. It's a fine job, except for the part where girls are dying while supposedly playing a game called "elevator surfing".
Heather doesn't buy the police's explanation and does a little sleuthing on her own. When she becomes a target, private investigator (and possible love interest) Cooper joins her efforts.