Hilary Duff's new book Elixir will be released on October 12, 2010 according to Amazon.
Amazon.de (Germany) has this full plot description. I'm not sure why this is on the German Amazon and not the USA one, but since it's on Amazon I assume it is legit.
Ever since she was small, Clea Rayner has been haunted by both a gift and curse. When she takes photos, extra pictures appear on the camera - photos she hasn't taken. These photos are a calling; she must find and go to their location, where she always discovers a tragedy that only she can stop. She has seen some harrowing things, and it's made her wary of opening her heart to anyone. Yet what haunts Clea most is not the dire situations she sees, but the mystery of her father, who disappeared two years ago and is now presumed dead. She has only one clue about what happened to him: a photograph that arrived after his disappearance. No matter how much she studies the picture, Clea can't tell where it is, but she carries it with her everywhere, just waiting for the revelation that will help her. That revelation comes on a trip to Colombia, where she meets Race; a strikingly handsome, magnetic and enigmatic stranger and despite Clea's reticence to open her heart, she feels an instant connection to Race that she can't explain. But whatever has brought them together is also threatening to tear them apart and as the mystery of her father's disappearance unravels, Clea discover that she has powers that are bigger than anything she could have anticipated...
MTV video with Hilary talking about the novel: