Big Dog had a good life, with everything that a dog could want. Sure, it was a little lonely sometimes, and the days could seem long, but still it was good. And then, one day, everything changed ... Adjusting to a new little dog in the house can be very challenging for some big dogs, but Big Dog, Little Dog shows that eventually, things have a way of working out for the best, and that soon it will be impossible to imagine life without a little dog around.