Five friends go to the lake but only four come back alive. Emily, Leah, Cecilia, Molly, and Kennedy end their summer with a sleepover and swimming at the local hot spot, but things between friends aren't always what they seem. Emily turns up dead and no one knows what happened to her... or do they? A mysterious letter found in her casket says otherwise, and it's up to the girls to find out which one of them is a killer before it's too late.