'Seven years ago, the Ballastian sisters' parents left them in the magical Straygarden Place, a house surrounded by tall silver grass and floating trees. They left behind a warning saying never to leave the house or go into the grass. "Wait for us," the note read. "Sleep darkly." Ever since then, the house itself has taken care of Winnow, Mayhap, and Pavonine--feeding them, clothing them, even keeping them company--while the girls have waited and...

On their a cross-country camping trip, Greg Heffley and his family find themselves stranded at an RV park that's not exactly a summertime paradise and when the skies open up and the water starts to rise, the Heffleys wonder if they can save their vacation--or if they're already in too deep.