SHELBY STARNER WAS 11 when she started writing songs on the old, out-of-tune upright in her parents’ basement in East Stroudsburg, Pa. She was 13 when a friend of a friend passed her tape along to Warner Bros.–which gave her a record deal and a backup band. Now 15, she’s got her first album, an upcoming tour and a topflight publicist–Madonna’s own Liz Rosenberg.

The heartfelt, piano-based songs on ““From in the Shadows’’ (out March 23) focus on the dark side of human relations: heartbreaks, insults and lies. Musically, Starner borrows from Tori Amos, but her central theme–wishing she were older than she is, coupled with horror at the way grown-ups carry on–is all her own. She hates the bubblegum pop of teen peers like Hanson, cringing to think anyone would throw her into that category. ““When anyone reminds me I’m only 15, I’m like, “Shhh! Don’t tell anybody!’ ’’ she says. ““Everyone will be like, “Who does she think she is? She’s just a girl!’ And that’s exactly what I would say.’’ Starner happily opted out of high school to do in-dependent study. She still lives with her parents, but she’s counting the days until she’s 18, when she’ll move to New York. This girl’s trying to grow up as fast as she can.