A MOUNTAIN LAKE HARBORS A HIDDEN PAST A charming lakeside cottage should be the perfect vacation spot for Nancy and her friends -- until Bess becomes convinced that they're sharing the place with ghosts. Strange thumps in the attic put them all on edge -- except there is no attic. Even worse, their living neighbors are giving them grief. A pair of bird-watching photographers sets dangerous traps in the woods, a summer camp director chases Nancy and...