Lily and the Lost Boy — Paula Fox

Newbery Medal winner Paula Fox depicts a fateful summer on the mysterious Greek island of Thasos in this “haunting tale” (TheNew York Times Book Review).
 
Lily Corey and her older brother, Paul, have been summering on the Greek island of Thasos with their parents. For Lily, it's been fun hanging out with her brother, exploring the island, and studying ancient mythology and archaeology -- until they meet Jack Hemmings.
 
When Paul and Jack become friends, Lily feels left out. She thinks Jack is a show-off and a fake. She also knows he's sad and lonely, yet she still wishes the boys would include her on their wild adventures. Then, one day, Jack shows off too much and something terrible happens . . .
 
Amid the wilds of an exotic Greek island, Lily and the Lost Boy is the “beautifully crafted” (Kirkus Reviews) story of a young girl coming of age and discovering her courage and compassion.