A walk in the park with Nana and Gramps is always a lot of fun, but they're terribly slow and their grandchild isn't allowed to race ahead. Walking dutifully behind them, the child is soon joined by a long line of fantastical characters: a bear, a monster from the sewers, a pirate and his crew. Those grandparents would never believe who else is on their walk, if only they'd look behind them.