Ring of endless light (Square Fish)

After a tumultuous year in New York City, the Austins are spending the summer on the small island where their grandfather lives. He's very sick, and watching his condition deteriorate as the summer passes is almost more than Vicky can bear. To complicate matters, she finds herself as the center of attention for three very different boys.Zachary Grey, the troubled and reckless boy Vicky met last summer, wants her all to himself as he grieves the loss of his mother. Leo Rodney has been just a friend for years, but the tragic loss of his father causes him to turn to Vicky for comfort--and romance. And then there's Adam Eddington. Adam is only asking Vicky to help with his research on dolphins. But Adam--and the dolphins--may just be what Vicky needs to get through this heartbreaking summer.