The Waters and the Wild
Deeply depressed Olivia whose parents are divorcing, leaving her vulnerable, is ripe for manipulation. And swimming star Blake is looking for someone just like her. Although her friend tries to warn her, Olivia falls for his ploys and accepts an invitation to go to the Adirondack resort camp of Lake Endor with his family.
But all is not as it seems at the 100 year old resort. Not only does Olivia discover that Blake is not the guy she thought he was, there is something sinister afoot, and things are not well. Pets and wild animals are found wantonly slaughtered or just disappear.
And there is something lying beneath the waters of Lake Endor. Something not of this world.
Mercedes Lackey
Mercedes Ritchie Lackey (born 1950) is an American writer of fantasy novels. Many of her novels and trilogies are interlinked and set in the world of Velgarth, mostly in and around the country of Valdemar. Her Valdemar novels form a complex tapestry of interaction between human and non-human protagonists with many different cultures and social mores.
Her other main world is one much like our own, but it includes clandestine populations of elves, mages, vampires, and other mythical beings. The Bedlam's Bard books describe a young man with the power to work magic through music; the SERRAted Edge books are about racecar driving elves; and the Diana Tregarde thrillers center on a Wiccan who combats evil.