Gr 4-7 Laurie, her family, and best friend plan to spend a restful week in Cabin 13 at a state park. Instead, a threatening note greets them and warns them that the place is haunted. The note is signed by Eleanor, who had died the summer before in a drowning accident. Eerie lights and additional notes strongly suggest the presence of ghosts. Laurie, an amateur detective, investigates. Within a week she discovers how Eleanor drowned and who is sending the threats and why. She also befriends a handicapped teenaged boy. Laurie is a level-headed heroine who makes her nervous mother and boy-crazy friend look silly. She doesn't believe in ghosts, and soon readers will be just as skeptical. Thus, the book lacks the terrifying suspense of a true ghost story, such as Hahn's Wait Till Helen Comes (Clarion, 1986). However, ``who-done-it'' fans will find enough suspects (an arrogant lifeguard, a friendly park ranger, and Eleanor's sister) and adventures to keep the plot moving along. Although the book is about teenagers, the literary style is aimed at the upper elementary readers. Holl's book is an additional purchase for the mystery shelves. Judy Greenfield, Rye Free Reading Room, N.Y.