In the Dark of the Night — John Saul

For Chicago couple Dan and Merrill Brewster, a summer at Pinecrest, a rambling lakeside house, is an deal vacation, and for their kids, Eric and Marci, Pinecrest is the perfect place to spend some time exploring. Eric and his friends discover a curious cache of objects stowed in a hidden room, but the boys' strange fascination with the forgotten possessions soon becomes an obsession. When a horrifying discovery surfaces, so does the chilling truth about the terrifying events that rocked the town seven years before, the mysterious disappearance of Pinecrest's previous resident, and a twisted legacy with a malevolent life of is own . . . and a bottomless hunger for new victims.