Clare's turning thirteen this summer and has decided to make a big change in her life. She's not giving up her messy-casual wardrobe, her comic book collection, or her interest in Japanese monster movies. But she is giving up her best friend. Of course, Elsa isn't your usual best friend. For one thing, she and Clare are complete opposites, in everything from clothing styles to favorite movies to personalities. But for another, Elsa doesn't even exist. Actually, for Clare, Elsa is very real: she's been Clare's imaginary friend since they were five years old. But now, Clare's decided it's time to let Elsa go.  However, Elsa seems to have other plans. "Let me just look at my watch," Elsa says as she glances at her bare wrist. "Yup, that's it, right on the nose. It's time for the 'I'm-too- old-for-an-imaginary-friend' speech. Um, I've heard it. Remember when we were seven? I miss seven. We never had to have these talks back then." Besides the fact that Elsa doesn't want to leave, Clare has to deal with all this growing- up stuff like falling in love with her teacher, making new friends while losing others, and reconnecting with her parents - all problems that kids everywhere face, but Clare does it in style.