Once upon a should-have-been-happy time, the earth is feeling sort of sad. From people to bugs and birds to forks, smiles have disappeared, and bad moods reign supreme. Then, from the outer reaches of Not-from-Here, come the Rocket Puppies! These impossibly cute canines hiccup bubbles that play songs, stop bees from stinging, and keep recesses rain-free. Slowly but surely, everyone’s frowns turn upside down. But not everyone wants to be cheerful. Snarly McBummerpants is determined to glom onto gloom. When he billows out Mopey Smoke, can the Rocket Puppies rally to defeat this new foe?