Review - The Deadly Sister / Eliot Schrefer 
Abby Goodwin is surely her sister Tabitha isn't a murderer. But her parents don't agree. Her friends don't agree. And the cops definitely don't agree. Tabitha is a drop-out, a stoner, a girl who's obsessed with her tutor, Clyde Andrews.until he ends up dead. Tabitha runs away, and leaves Abby following the track of clues.
