Samantha and her friends set off on a secret summertime exploration that lands them in the middle of a dangerous storm. Part of the American Girls series. Samantha and her family are spending the summer at Piney Point Grandmary s home in the mountains. One day Samantha and the twins Agnes and Agatha find a sketchbook made by Samantha s mother. In it Samantha sees a beautiful waterfall she had visited with her parents long ago before they died in a boating accident. Using the sketchbook as a map Samantha and the twins set off. When their secret exploration puts them in the middle of a dangerous storm Samantha must save the day.