Don't Go in the Basement (Sweet Valley Twins #109)

Principal Clark is hiding something...
When Jessica Wakefield started a house-sitting service with her twin sister, Elizabeth, she never imagined their first client would be Mr. Clark, the school principal. Elizabeth is nervous, but Jessica is psyched. She wants some juicy gossip about Mr. Clark's private life, and snooping around his house will be a great way to find it.But Jessica finds more than she bargained for: a butcher knife in the hall closet, and a long lock of hair in the dresser. Then, in the cobwebs of Mr. Clark's dark, damp basement, something makes Jessica's heart stand still. Could her principal be a murderer?