i found this to be an entertaining quick read (it's only about 150 pages). it's a great story for a young teen -- especially one who's just starting to babysit.
FROM THE BACK OF THE BOOK:
Sue knows she shouldn't be sneaking around the Anderson's Property after little Adam goes to bed. But babysitting can be so boring. Then Sue stumbles upon a strange envelope. An envelope with a mystery inside -- a deadly mystery. Will Sue survive the night?